o

oak < middle english oke < old english ac / old norse eik (= oak tree) < proto-germanic *aiks {> swedish ek, danish eg, dutch eik, german Eiche}.

oar < middle english or < old english ar < proto-germanic *airo.

oasis < french oasis < late latin oasis < ancient greek όασις | oasis < egyptian wh’t (= pit, depression).

oath < middle english oth < old english að < proto-germanic *aithaz < I.E. *oi-to- (= an oath).

obedience < middle english obedience < old french obedience (= submission) < latin oboedientia (= obedience) < oboediens [gen. obedientis], present participle of ob(o)edo [inf. ob(o)edire] (= listen to, obey) < ob (= to, over) + audio [inf. audire] (= listen, hear).

obelisk < middle french obélisque < latin obeliscus < ancient greek οβελίσκος | obheliskos (= small spit, obelisk, leg of a compass), a diminutive of οβελός | obhelos (= a spit, pointed pillar, obelisk).

obese < latin obesus (= fat, stout, plump) < obesus, past participle of obedo [inf. obedere] (= eat all over, devour) < ob (= to, over) + edo [inf. edere] (= eat).

obey < middle english obeien < old french obeir (= obey) < latin ob(o)edo [inf. ob(o)edire] (= listen to, obey) < ob (= to, over) + audio [inf. audire] (= listen, hear).

obituary < medieval latin obituarius (= a record of one’s death) < latin obitus (= departure) [an euphemism for death] < obeo [inf. obire] (= go toward) < ob (= to, over) + eo [inf. ire] (= go).

object < middle english object < old french object < medieval latin objectum (= thing put before) < latin objectum, of objectus (= lying before, opposite), neuter past participle of objicio [inf. objicere] (= to present, oppose) < ob (= to, over) + jacio [inf. jacere] (= to throw).

oblige < middle english obligen < old french obligier (= commit, pledge) < latin obligo [inf. obligare] (= to bind, put under obligation) < ob (= to, over) + ligo [inf. ligare] (= to bind).

oblique < middle english oblique < old french oblique < latin obliquus (= slanting, sidelong, indirect) < (?) ob (= to, over) + licinus (= bent upward).

oblivion < middle english oblivioun (= lost of memory) < old french oblivion < latin oblivio (= forgetfulness) < obliviscor [inf. oblivisci] (= forget) < (?) ob (= to, over) + levis (= smooth).

oboe < italian oboe < french hautbois < haut (= high, loud) + bois (= wood).

obscure < middle english obscure < old french o(b)scur (= dark, clouded) < latin obscurus (= dark, dusky, unknown) < ob (= to, over) + -scurus (= covered).

observe < middle english observen < old french observer / osserver (= watch over, follow) < latin observo [inf. observare] (= watch over, note, guard) < ob (= to, over) + servo [inf. servare] (= watch, keep safe).

obsess < middle english obsess < latin obsessus, past participle of obsideo [inf. obsidere] (= sit opposite to, watch closely, besiege) < ob (= to, over) + sedeo [inf. sedere] (= to sit).

obstacle < middle english obstacle < old french o(b)stacle (= opposition, obstruction) < latin obstaculum (= hindrance, obstacle) < obsto [inf. obstare] (= stand before, hinder) < ob (= to, over) + sto [inf. stare] (= to stand).

obtain < middle english obteinen < old french obtenir (= acquire, obtain) < latin obtineo [inf. obtinere] (= hold, hold fast, acquire) < ob (= to, over) + teneo [inf. tenere] (= to hold).

obvious < middle english obvious < latin obvius (= open, exposed) < obviam (= in the way) < ob (= to, over) + viam, accusative of via (= way, road).

occasion < middle english occasioun < old french ochaison / ocasion (= reason, excuse, opportunity) < occasio (= opportunity, appropriate time, cause) < occasus, past participle of occido [inf. occidere] (= fall down, go down) < ob (= to, over) + cado [inf. cadere] (= to fall).

occupy < middle english occupien < old french oc(c)uper (= occupy, hold, seize) < latin occupo [inf. occupare] (= take over, seize, possess) < ob (= to, over) + capio [inf. capere] (= take, hold).

occur < middle french occurrer (= happen unexpectedly) < latin occuro [inf. occurrere] (= run to meet, run against) < ob (= to, over) + curro [inf. currere] (= to run).

ocean < middle english occean < old french occean < latin oceanus < ancient greek ωκεανός | ōkeanos (= the great river surrounding the Earth).

Oceania < modern latin Oceania < french Océanie < old french occean < latin oceanus < ancient greek ωκεανός | ōkeanos (= the great river surrounding the Earth).

ochre < middle english ocre / oker < old french ocre < medieval latin ocra < latin ochra < ancient greek ώχρα | ōkhra < ωχρός | ōkhros (= pale yellow).

octave < medieval latin octava < latin octava [dies] (= eighth [day]) < octava, female of octavus (= eighth) < octo (= eight) {> italian otto, spanish ocho, french huit} < I.E. *octo(u)- (= eight) {> ancient greek οκτώ | oktō, sanskrit astau}.

Octavian < latin Octavian < Octavius < octavus (= eighth [child in birth order]) < octo (= eight) < I.E. *octo(u)- (= eight).

October < old english October < latin October [mensis] (= eight [month]) [of the old Roman calendar, which began with March] < octo (= eight) + [suffix] -ber (< -bris).

octopus < ancient greek οκτόπους | oktōpous < οκτώ | oktō (= eight) + πους | pous (= foot).

odd < middle english odde < old norse oddi (= third or additional number, angle) < proto-germanic *uzdaz (= pointed upward).

ode < middle french ode < late latin ode (= lyric song) < ancient greek ω_ιδή | ō_idhē < αοιδή | aoedhē (= song, ode) < αείδω | aoedhō (= to sing).

odeon < ancient greek ωδείον | ōdhoeon (= building for musical performance) < ancient greek ω_ιδή | ō_idhē (= song, ode) < αοιδή | aoedhē (= song, ode) < αείδω | aoedhō (= to sing).

odor < middle english odor < anglo-french odour < old french odor (= smell, perfume, fragrance) < latin odor (= a smell, scent) < I.E. *hed- (= to smell).

odyssey < latin Odyssēa < ancient greek Οδύσσεια | Odhyssoea [the second poem of Homer, describing the adventures of Odysseus after the fall of Troy (described in his first poem, Iliad)] < ancient greek Οδυσσεύς | Odhyssefs (= Odysseus, Ulisses), king of Ithaca island.

of < old english of < æf (= away, away from) < proto-germanic *af < I.E. *apo- (= off, away).

off < middle english off < old english of < æf (= away, away from) < proto-germanic *af < I.E. *apo- (= off, away).

offend < middle english offenden < old french ofendre (= hit, attack) < latin offendo [inf. offendere] (= hit, thrust, strike against) < ob (= to, over) + -fendo [inf. -fendere] (= to strike).

offer < middle english offeren < old english ofrian (= bring forward, show, exhibit) < latin offero [inf. offerre] (= bring before, present, bestow) < ob (= to, over) + fero [inf. ferre] (= bring, carry).

office < middle english office < anglo-french / old french ofice (= place, function, divine service) < latin officium (= service, function, kindness, official duty) < opificium (= work-doing) < ops [gen. opis] (= power, might) + facio [inf. facere] (= make, do).

often < middle english often < old english oft (= repeatedly, frequently) < proto-germanic *ufta- (= frequently) < (?) I.E. *upo (= under).

oil < middle english oil < anglo-french / old french olie < old french oile / uile (= oil) < latin oleum (= olive oil) < ancient greek έλαιον | elaeon (= olive oil) < ελαία | elaea (= olive tree, olive).

ointment < middle english oynement < old french oignement (= ointment, salve, unguent) < vulgar latin *unguimentum < latin unguentum (= ointment) < unguo [inf. unguere] (= to anoint with ointment).

o.k. < (?) an abbreviation [with jocular misspelling] of oll korrect (= all correct), in Boston and New York [1839], as an election slogan by the boosters of Martin Van Buren, in allusion to his nickname Old Kinderhook (< Kinderhook, a village of N.Y., where he was born).

Olaf < old norse An-leifr (= ancestor’s relic) < old high german ano (= ancestor) + leifr, related to old english læfan (= to leave).

old < old english ald / eald (= antique, ancient, elder, mature) < proto-germanic *althaz (= grown up, adult) < I.E. *al-₍₂₎ (= grow, nourish).

Oleg < russian Oleg < norse Helge < Helgi (= holy) < proto-germanic *hailaga < I.E. *kailo- (= whole, uninjured).

Olga < russian Olga < norse Helga (= holy) < proto-germanic *hailaga < I.E. *kailo- (= whole, uninjured).

oligarchy < middle french oligarchie < ancient greek ολιγαρχία | oligharkhia (= government by the few) < ολίγος | olighos (= small, few) + άρχω | arkhō (= to rule).

olive < middle english olive < old french olive < latin oliva (= olive, olive tree) < ancient greek ελαία | elaea (= olive, olive tree).

Oliver < middle english Oliver < french Olivier [by influence of olive (= olive tree)] < middle low german Alfihar (= elf-host, elf-army) < alf (= elf) + hari (= host, army).

Olivia < italian Olivia < latin oliva (= olive, olive tree) < ancient greek ελαία | elaea (= olive, olive tree).

Olympic < ancient greek Ολυμπικός | Olympikos < 1. Όλυμπος | Olympos, a mountain [home of the twelve great gods] or 2. Ολυμπιακός | Olympiakos < Ολυμπία | Olympia, a town [with a famous temple of Zeus, where every four years athletic contests were held in his honor from 776 B.C.].

omega < middle english omega < medieval greek ωμέγα | ōmegha < ancient greek ω μέγα | ō megha (= big “o”) [long o in pronunciation, in contrast to όμικρον | omicron (= small “o”)] < [letter] ω + μέγα, neuter of μέγας | meghas (= big).

omelet < french omelette < alemette < alemele (= blade, omelet) < (?) la lemelle < latin lamella (= thin plate), a diminutive of lamina (= plate, layer).

omen < latin omen [gen. ominis] (= foreboding, augury) (< old latin osmen).

omerta < italian omertà < [dialectal] umilta (= humility) [in reference to submission of its members] < latin humilitas (= lowness) < humilis (= on the ground, humble) < humus (= earth).

omg < [1994] an abbreviation of oh my God.

omicron < middle english omicron < medieval greek όμικρον < ancient greek ο μικρόν (= small “o”) [short o in pronunciation, in contrast to ωμέγα | ōmega (= big “o”)] < [letter] o + μικρόν, neuter of μικρός | mikros (= small).

omit < middle english omitten < latin omitto [inf. omittere] (= let go, let fall) < ob (= to, over) + mitto [inf. mittere] (= let go, send).

omnibus < french [voiture] omnibus (= [carriage] for all) {> english bus} < latin omnibus, dative plural of omnis (= all).

omnipotence < middle english omnipotens < old french omnipotence < late latin omnipotentia (= almighty power) < latin omnipotens (= all-powerful, almighty) < omnis (= all) + potens [gen. potentis] (= powerful).

on < old english on < an (= in, on, into) < proto-germanic *ana (= on) < I.E. *an-₍₁₎ (= on).

once < middle english anes < one + [adverbial genitive] -s.

one < middle english one < old english an (= one) < proto-germanic *ainaz {> old norse einn, danish een, dutch een, gothic ains, german ein} < I.E. *oi-no- (= one, unique) {> latin unus}.

oneiric < ancient greek όνειρος, όνειρον | onoeros, onoeron (= a dream).

onion < middle english oinyon / ungeon / unione < anglo-french union / old french oignon (= onion) < latin unio (= unity, a kind of onion [in a string (a twist) of onions]) < unus (= one, unique).

only < middle english onli < old english ænlic / anlic (= unique, solitary) < an (= one) + -lic (= -like).

onomatology < ancient greek όνομα | onoma [gen. ονόματος | onomatos) (= name) + -λογία | -loghia (= study) (< λόγος | loghos (= a speaking) < λέγω | leghō (= speak)).

ontology < modern latin ontologia < ancient greek ον | on [gen. όντος | ontos], neuter present participle of ειμί | oemi (= I am) + -λογία | -loghia (= study) (< λόγος | loghos (= a speaking) < λέγω | leghō (= speak)).

onyx < middle english oneche / onix < old french oniche < latin onyx < ancient greek όνυξ | onyx (= claw, nail, onyx-stone).

oology < ancient greek ωόν | ōon (= egg) + -λογία | -loghia (= study) (< λόγος | loghos (= a speaking) < λέγω | leghō (= speak)).

opacity < french opacité < latin opacitas (= shade, shadiness) < opacus (= shaded, dark).

opal < middle french opalle < late latin opalus < sanskrit upala-s (= gem, precious stone).

opaque < middle english opake < latin opacus (= shady, dark, obscure).

open < old english open < proto-germanic *upana- (= put up, set up) {> old norse opinn, german offen} < I.E. *upo (= under, over).

opera < italian opera (= work, composition) < latin opera (= work, effort) < operor [inf. operari] (= to work) < opus [gen. operis] (= a work) < I.E. *op- (= to work).

operation < middle english operation < old french operacion (= operation, working, proceedings) < latin operatio (= a working, operation) < operor [inf. operari] (= to work) < opus [gen. operis] (= a work).

Ophelia < ancient greek ωφέλεια | ōpheloea (= help, aid) < ωφελώ | ōphelō (= to help, aid) < όφελος | ophelos (= advantage, help) < I.E. *obhel- (= to avail).

ophidian < ancient greek οφίδιον | ophidhion, a diminutive of όφις | ophis (= serpent, snake).

Ophiuchus < latin ophiuchus < ancient greek οφιούχος | ophioukhos (= holding a serpent) < όφις | ophis (= serpent, snake) + έχω | ekhō (= hold, have).

ophthalmic < latin ophthalmicus < ancient greek οφθαλμικός | ophthalmikos (= of the eyes) < οφθαλμός | ophthalmos (= eye).

opinion < middle english opinioun < old french opinion (= opinion, view) < latin opinio (= opinion, conjecture, belief) < opinor [inf. opinari] (= think, judge, suppose).

opium < middle english opium < latin opium < ancient greek όπιον | opion (= poppy juice, poppy), a diminutive of οπός | opos (= plant juice) < I.E. *sokwo- (= juice, resin).

opponent < latin opponens [gen. oponentis], present participle of oppono [inf. opponere] (= set opposite, oppose) < ob (= to, over) + pono [inf. ponere] (= to put, place).

opportune < middle english opportune < old french opportune < latin opportunus (= fit, convenient, favorable) < [ventus] ob portum [veniens] (= [wind] toward a port [coming]) < ob (= to, over) + portus (= port, harbor).

opposite < middle english opposite < old french op(p)osite (= contrary) < latin oppositus (= opposite), past participle of oppono [inf. opponere] (= set opposite, oppose) < ob (= to, over) + pono [inf. ponere] (= to put, place).

optic < middle english optik < old french obtique / optique < medieval latin opticus (= of seeing) < ancient greek οπτικός | optikos (= of seeing) < οπτός | optos (= visible) < stem οπ- | op- < I.E. *okw- (= to see).

optimum < latin optimum, neuter of optimus (= best), superlative of bonus (= good).

option < middle english option < french option < latin optio (= choice, liberty to choose) < opto [inf. optare] (= to desire, choose).

opus < latin opus [gen. operis] (= work, labor, exertion) {> spanish obra, italian opera, french oeuvre} < proto-italic *opes- (= work) < I.E. *op- (= to work).

or < middle english or (= either, else, otherwise) < old english oþþe (= either, or).

oracle middle english oracle < old french oracle (= temple, oracle) < latin orac(u)lum (= divine announcement, oracle) < oro [inf. orare] (= to pray, beseech).

oral < late latin oralis (= of the mouth) < latin os [gen. oris] (= mouth, opening) < I.E. *os- (= mouth).

orange < middle english orange < old french orange / orenge < medieval latin orenge < italian arancia < narancia < arabic naranj < persian narang < sanskrit naranga-s (= orange tree).

orangutan < french orang-ou-tang < dutch orang-outang < malay orang utan (= man of the forest) < orang (= man) + (h)utan (= forest, wilderness).

oratorio < italian oratorio < late latin oratorium (= a place of prayer, oratory, chapel) < oratorium, neuter of latin oratorius (= of praying) < oro [inf. orare] (= to pray, beseech).

orbit < middle english orbit < old french orbite < latin orbita (= wheel track, path, course).

orca < orc / ork < french orque < latin orca (= cetacean, a kind of whale).

orchard < old english orceard (= fruit garden) < ortgeard < (?) wortgeard < wyrt (= vegetable, root)) + geard (= garden).

orchestra < middle english orchestra < latin orchestra < ancient greek ορχήστρα | orkhēstra (= the place in a theater for the chorus of dancers) + ορχούμαι | orkhoumae (= to dance).

orchid < modern latin orchideæ < latin orchis, a kind of orchid < ancient greek όρχις | orkhis (= testicle) [because the root of this plant looks like testicle].

order < middle english order < old french ordre (= position, estate, rule) < ordene < latin ordo [gen. ordinis] (= row, rank, series, arrangement).

ordinary < middle english ordinarie < old french ordinarie (= usual, ordinary) < latin ordinarius (= customary, regular, usual) < ordo [gen. ordinis] (= row, rank, series, arrangement).

ore < middle english ore < a merge of old english ora (= ore, unworked metal) + old english ar (= brass, copper, bronze) (< proto-germanic *ajiz- < I.E. *aus-₍₂₎ (= gold)).

oregano < american spanish / spanish oregano < latin origanus / origanum < ancient greek ορείγανον | oroeghanon < όρος | oros (= mountain) + γάνος | ghanos (= brightness, ornament).

organ < [old english organe / old french orgene] (= musical instrument) < latin organum (= organ, musical instrument) < ancient greek όργανον | orghanon (= tool, musical instrument, organ of the body) < I.E. *werg- (= do).

organization < middle english organisacioun (= structure of the body, act of organizing) < medieval latin organizatio (= an organizing) < organizo [inf. organizare] (= organize) < latin organum (= organ, musical instrument) < ancient greek όργανον | orghanon (= tool, musical instrument, organ of the body).

orgasm < modern latin orgasmus / french orgasme < ancient greek οργασμός | orghasmos (= excitement, swelling) < οργώ | orghō (= swell, be excited, be in heat) < οργή | orghē (= impulse, excitement, anger).

orgy < orgies [plural] < middle french orgies < latin orgia < ancient greek όργια | orghia [plural] (= secret rites for a god, especially Dionysus) < I.E. *werg- (= do, werk) {> ancient greek έργον | erghon}.

oriel < middle english oriel < old french oriol (= hall, vestibule) / medieval latin oriolum (= porch, small room, gallery) < (?) vulgar latin *auraeolum < aulaeolum < a diminutive of latin aulaeum (= curtain).

orient < middle english orient < old french orient (= east) < latin oriens [gen. orientis] (= the rising sun, the east) < oriens, present participle of orior [inf. oriri] (= to rise).

origami < japanese origami < ori (= fold) + kami (= paper).

origin < middle english origin (= ancestry, race) < latin origo [gen. originis] (= a rise, beginning, source, descent, birth) < orior [inf. oriri] (= to rise, be born, start).

Orlando < italian Orlando < french Roland < old high german Hrodland < hrod (= famous) + land).

Orleans < french Orléans < latin Aurelianum < Aurelian, an emperor.

ornament < middle english ournement < old french ornement (= decoration), < latin ornamentum (= apparatus, equipment, decoration) < orno [inf. ornare] (= to equip, adorn) < ordo (= row, rank, series, arrangement).

ornithology < modern latin ornithologia < ancient greek όρνις | ornis [gen. όρνιθος | ornithos] (= bird) + -λογία | -loghia (= study) (< λόγος | loghos (= a speaking) < λέγω | leghō (= speak)).

orphan < middle english orphan < late latin orphanus (= parentless child) < ancient greek ορφανός | orphanos (= orphaned, without parents) < *όρφος | *orphos (= bereft).

orthodox < middle english orthodox < late latin orthodoxus < ancient greek ορθόδοξος | orthodhoxos (= with the right opinion) < ορθός | orthos (= right, true, correct) + δόξα | dhoxa (= opinion) (< δοκώ | dhokō (= seem, believe)).

orthopedic < french orthopédique < orthopédie < ancient greek ορθός | orthos (= right, straight, correct) + παις | paes [gen. παιδός | paedhos) (= child).

Osbo(u)rn(e) < scandinavian Osbo(u)rn(e) (= god-bear) < os (= god) + proto-germanic *beranan (= bear).

Oscar < old english Osgar (= god’s spear) < os (= god) + gar (= spear).

oscillation < french oscillation < latin oscillatio (= a swinging) < oscillo [inf. oscillare] (= to swing) < oscillum (= a swing) < (?) ob(s) (= to, over) + cillo (= move).

Oslo < norwegian Oslo < (?) 1. old norse os (= estuary, river mouth) or 2. old norse As, a god + Lo, a river.

Osmond < old english Osmund < os (= god) + -mund (= protection).

osmosis < osmose / osmosis, a shortening of endosmose / endosmosis < ancient greek ένδον | endon (= inward) + ωσμός | ōsmos (= a pushing) (< ωθώ | ōthō (= push)).

ossification < latin os [gen. ossis] (= bone) + -fication (= a making or causing) (< facio [inf. facere] (= make, do)).

ostentation < middle english ostentacioun < old french ostentacion < latin ostentatio (= exhibition, vain display) < ostento [inf. ostentare] (= to display) < ostendo [inf. ostendere] (= to show, exhibit, display) < ob (= to, over) + tendo [inf. tendere] (= to stretch).

osteoporosis < ancient greek όστεον | osteon (= bone) + πόρος | poros (= passage, pore).

ostracism < middle french ostracisme < ancient greek οστρακισμός | ostrakismos (= ostracism) < οστρακίζω | ostrakizō (= to ostracize) < όστρακον | ostrakon (= potsherd) [because in Athens used to write the name of whom wanted to vote for exile upon a potsherd (a material for writing, easy to find it in the streets from the broken vessels)].

ostrich < middle english ostrich / hostriche / estrich < old french ostruce / medieval latin ostrica / ostrigius < vulgar latin avis struthio < latin avis (= bird) + late latin struthio (= ostrich) (< ancient greek στρουθίον | strouthion (= little sparrow, ostrich) < στρουθός [μεγάλη] | strouthos [meghalē] (= [big] sparrow)).

Oswald < old english Osweald (= god-power) < old english os (= god) + old english (ge)weald (= power).

other < old english oþer (= the second of two, one of the two, additional) < proto-germanic *anthera- {> old norse annarr, dutch ander, german ander}.

Otto < german Otto < old high german Odo / Udo < proto-germanic *aud- (= wealth).

ouch < german outch, cry of pain < autsch.

ought < old english ahte (= owned, possessed), past tense of agan (= to own, possess).

ounce < middle english ounce < old french once / unce < latin uncial (= one-twelfth part [of a pound]) < latin unus (= one) [the abbreviation oz. is from older italian onza].

our < old english ure (= of us, pertaining to us) [genitive plural] < proto-germanic *ons < I.E. *nes- (= we) {> latin nos}.

out < old english ut (= out, without) < proto-germanic *ūt- < I.E. *uidh- (= up, out, on high).

outrage < middle english outrage < old french outrage (= harm, damage) < oltrage < vulgar latin *ultraticum (= excess) < latin ultra (= beyond).

oval < middle french ovalle (= oval figure) < medieval latin ovalis (= of eggs) < latin ovum (= egg) < I.E. *ōwyo  / *ōyyo  (= egg).

ovary < modern latin ovarium (= ovary) < medieval latin ovaria (= the ovary of a bird) < latin ovum (= egg) < I.E. *ōwyo  / *ōyyo  (= egg).

ovation < middle french ovation < latin ovatio (= a triumph, rejoicing) < ovo [inf. ovare] (= to triumph, rejoice, exult) < (?) imitative origin.

oven < old english ofen (= furnace) < proto-germanic *ukhnaz {> old norse ofn, dutch oven, german Ofen} < I.E. *aukw- (= cooking pot).

over < old english ofer (= beyond, above, upon) < proto-germanic *uberi {> old norse yfir, german über) < I.E. *uper (= over) {> ancient greek υπέρ | yper}.

overt < middle english overt (= open, unfastened) < old french overt, past participle of ovrir (= to open) < latin aperio [inf. aperire] (= to open, uncover).

overture < middle english overture < old french overture (= opening, proposal) < latin apertura (= opening) < aperio [inf. aperire] (= to open, uncover).

owe < old english agan (= have, own) < proto-germanic *aiganan (= to possess) < I.E. *aik- (= to possess).

Owen < celtic Owen < gaelic Eòghann / old irish Eogán / old welsh Eugein, Ougein < latin Eugenius < ancient greek Ευγένιος | Evghenios < ευγενής | evghenēs (= nobleman, gentle) < ευ | ef, ev (= well) + γένος | ghenos (= parentage).

owl < middle english oule < old english ule (= owl) < proto-germanic *uwwalon- < I.E. *u(wa)l-, of imitating origin.

own < middle english ahnen / ounen (= to possess, have) < old english geagnian < agan (= have, own) < proto-germanic *aiganan (= to possess) < I.E. *aik- (= to possess).

own < middle english ouen < old english agen (= possessed by) < proto-germanic *aiganaz (= possessed, owned) < I.E. *aik- (= to possess).

ox < middle english oxe < old english oxa (= ox) < proto-germanic *ukhson {> old norse oxi, middle dutch osse, gothic auhsa, german Ochse} < I.E. *uks-en- (= male animal) {> welsh ych, middle irish oss, avestan uxshan-, sanskrit uksa}.

Oxford < middle english Oxforde < old english Oxnaforda (= oxen ford) < ox + ford.

oxide < french oxide < oxygène (= oxygen) + acide (= acid).

oxygen < french oxygène < ancient greek οξύς | oxys (= sharp, acid) + stem γεν- | ghen-, γον- | ghon- of γίγνομαι | ghighnomae (= become, produce) [so called because joined with elements produces acid].

oxymoron < ancient greek οξύμωρον | oxymōron, neuter of οξύμωρος | oxymōros (= pointedly foolish) < οξύς | oxys (= sharp, pointed) + μωρός | mōros (= stupid).

oyster < middle english oistre < old french oistre / uistre < latin ostreum (= oyster) < ancient greek όστρεον | ostreon (= oyster) < I.E. *ost- (= bone).

ozone < german Ozon < ancient greek όζον | ozon, neuter present participle of όζω | ozō (= to smell) [so called for its pungent odor].