| Same word as o.k., ok, okay | Same word as O.K., okay | Same word as oafish |
| Same word as oaken | Same word as obdurate | Same word as obdurate, obstinate |
| Same word as obedient (vs. disobedient) | Same word as obese | Same word as obey |
| Same word as obfuscate | Same word as object | Same word as objectify |
| Same word as objectionable | Same word as objectionable, obnoxious | Same word as objective |
| Same word as objective (vs. subjective) | Same word as objurgate | Same word as oblanceolate |
| Same word as obligate | Same word as obligate,oblige | Same word as obligated(predicate) (vs. unobligated) |
| Same word as obligatory | Same word as obligatory (vs. optional) | Same word as oblige |
| Same word as oblige, obligate | Same word as oblige,obligate | Same word as obliged(predicate) |
| Same word as oblique | Same word as oblique (vs. parallel) (vs. perpendicular) | Same word as oblique-angled |
| Same word as obliterable | Same word as obliterate | Same word as obliterate, obliterated |
| Same word as oblivious | Same word as oblivious(predicate) | Same word as oblong |
| Same word as obovate | Same word as obscene | Same word as obscure |
| Same word as obscure, obnubilate | Same word as obscure,obliterate | Same word as obscure,obnubilate |
| Same word as obsequious | Same word as observable | Same word as observant |
| Same word as observant, observing | Same word as observational | Same word as observe |
| Same word as observed | Same word as obsess | Same word as obsessed |
| Same word as obsessional, obsessive | Same word as obsessive-compulsive | Same word as obsolesce |
| Same word as obsolescent | Same word as obsolete | Same word as obstinate |
| Same word as obstipate | Same word as obstreperous | Same word as obstruct |
| Same word as obstruct, obturate, occlude | Same word as obstructed (vs. unobstructed) | Same word as obstructive |
| Same word as obtain | Same word as obtainable | Same word as obtrude |
| Same word as obtrusive | Same word as obtund | Same word as obtuse |
| Same word as obtuse | Same word as obviate | Same word as obviating(prenominal) |
| Same word as obvious (vs. unobvious) | Same word as occasion | Same word as occasional |
| Same word as occasional(prenominal) | Same word as occidental | Same word as occidentalize, occidentalise |
| Same word as occluded | Same word as occluded, | Same word as occult |
| Same word as occult,orphic | Same word as occupied | Same word as occupy |
| Same word as occur | Same word as occurrent | Same word as oceangoing |
| Same word as oceanic | Same word as ocher, ochre | Same word as octosyllabic |
| Same word as ocular | Same word as odd | Same word as odd-job(prenominal) |
| Same word as odd-pinnate | Same word as oddish | Same word as odds-on |
| Same word as odious | Same word as odoriferous | Same word as odoriferous, odorous |
| Same word as odorize, odourise | Same word as odorless (vs. odorous), odourless | Same word as odorous (vs. odorless) |
| Same word as oecumenic, oecumenical | Same word as oecumenical | Same word as of age(predicate) |
| Same word as of sound mind(predicate) | Same word as of the essence(predicate) | Same word as of unsound mind(predicate) |
| Same word as off | Same word as off (vs. on) | Same word as off the beaten track(predicate), out-of-the-way(prenominal) |
| Same word as off the hook(predicate) | Same word as off, off, polish off | Same word as off-and-on(prenominal) |
| Same word as off-base | Same word as off-center, off-centered | Same word as off-color |
| Same word as off-color, off-colour | Same word as off-guard(prenominal), off guard(predicate), off one's guard(predicate), off his guard, off her guard, off your guard | Same word as off-key |
| Same word as off-limits, out-of-bounds(predicate) | Same word as off-putting | Same word as off-the-rack, off-the-shelf, off-the-peg |
| Same word as off-the-shoulder | Same word as off-the-wall, outlandish, outre | Same word as off-white |
| Same word as offbea | Same word as offend | Same word as offend, offend |
| Same word as offend,outrage | Same word as offended | Same word as offenseless, offenceless |
| Same word as offensive | Same word as offensive (vs. defensive) | Same word as offensive (vs. inoffensive) |
| Same word as offensive (vs. inoffensive) | Same word as offer | Same word as offer, offer up |
| Same word as offer,oneself | Same word as offhand, offhanded | Same word as offhand, offhanded, off-the-cuff |
| Same word as officer | Same word as official | Same word as official (vs. unofficial) |
| Same word as officialize, officialise | Same word as officiate | Same word as offish |
| Same word as offload | Same word as offsaddle | Same word as offset |
| Same word as offset, set off | Same word as offshore | Same word as offstage |
| Same word as ogle | Same word as oil | Same word as oil-bearing |
| Same word as oil-fired | Same word as oily | Same word as oily, oleaginous |
| Same word as oily,oleaginous | Same word as old | Same word as old (vs. new) |
| Same word as old (vs. young) | Same word as old(prenominal) | Same word as old(prenominal), |
| Same word as old, older | Same word as old, onetime(prenominal), one-time(prenominal), quondam(prenominal), sometime(prenominal | Same word as old-fashioned, old-hat(predicate |
| Same word as old-hat | Same word as old-maidish, old-womanish | Same word as old-time, quaint, olde worlde |
| Same word as old-world | Same word as olden | Same word as older |
| Same word as oldish | Same word as oldline, old-line | Same word as oleophilic (vs. oleophobic) |
| Same word as olive | Same word as olive-brown | Same word as olive-colored, olive-coloured |
| Same word as olive-drab | Same word as olive-grey, olive-gray | Same word as olivelike, olive-like |
| Same word as olympian | Same word as omen | Same word as ominous |
| Same word as omissible | Same word as omit | Same word as omnibus(prenominal) |
| Same word as omnifarious | Same word as omnipotent | Same word as omnipresent |
| Same word as omniscient | Same word as omnivorous (vs. insectivorous) (vs. carnivorous) (vs. herbivorous) | Same word as on (vs. off) |
| Same word as on fire(predicate) | Same word as on guard, on one's guard(predicate), upon one's guard(predicate), on your guard | Same word as on hand(predicate) |
| Same word as on tap(predicate) | Same word as on the fence(predicate) | Same word as on the go(predicate) |
| Same word as on the hook(predicate) | Same word as on the job(predicate | Same word as on the loose(predicate) |
| Same word as on the nose, on the button | Same word as on the offensive(predicate) | Same word as on the table |
| Same word as on trial | Same word as on-key | Same word as on-line (vs. off-line), online |
| Same word as on-line(prenominal), online | Same word as on-site (vs. off-site) | Same word as on-the-spot(prenominal), on-the-scene(prenominal) |
| Same word as oncoming | Same word as one | Same word as one hundred |
| Same word as one hundred fifteen | Same word as one hundred fifty | Same word as one hundred fifty-five |
| Same word as one hundred five, | Same word as one hundred forty, | Same word as one hundred forty-five |
| Same word as one hundred ninety | Same word as one hundred one | Same word as one hundred seventy |
| Same word as one hundred seventy-five | Same word as one hundred sixty | Same word as one hundred sixty-five |
| Same word as one hundred ten, | Same word as one hundred thirty | Same word as one hundred thirty-five |
| Same word as one hundred twenty | Same word as one hundred twenty-five | Same word as one thousand |
| Same word as one(prenominal) | Same word as one(prenominal), one and only(prenominal) | Same word as one, 1, i, ane |
| Same word as one-armed | Same word as one-celled | Same word as one-dimensional |
| Same word as one-eared | Same word as one-eyed | Same word as one-handed |
| Same word as one-horse | Same word as one-man(prenominal), one-person(prenominal), one-woman(prenominal) | Same word as one-member |
| Same word as one-on-one | Same word as one-on-one, man-to-man | Same word as one-party |
| Same word as one-seeded, one-seed | Same word as one-sided | Same word as one-step |
| Same word as one-to-one | Same word as one-way | Same word as one-winged |
| Same word as one-year-old | Same word as ongoing, on-going | Same word as only |
| Same word as onshore | Same word as ooh | Same word as ooze |
| Same word as ooze out, ooze | Same word as ooze through | Same word as oozing, oozy |
| Same word as opacify | Same word as opalesce | Same word as opalescent, opaline |
| Same word as opalize, opalise | Same word as opaque | Same word as opaque (vs. clear) |
| Same word as open | Same word as open (vs. closed) | Same word as open (vs. closed), opened |
| Same word as open (vs. shut), unfastened | Same word as open fire | Same word as open up |
| Same word as open(prenominal) | Same word as open, open up | Same word as open, opened |
| Same word as open-air(prenominal) | Same word as open-and-shut | Same word as open-chain |
| Same word as open-collared | Same word as open-ended | Same word as open-minded |
| Same word as open-plan | Same word as opencast, opencut | Same word as openhanded |
| Same word as openhearted | Same word as opening (vs. closing) | Same word as openmouthed |
| Same word as operable, operational | Same word as operable, practicable | Same word as operate |
| Same word as operate on, operate | Same word as operate, control | Same word as operate, run |
| Same word as operational (vs. nonoperational) | Same word as operational, in operation(predicate), operating(prenominal) | Same word as operative |
| Same word as operative (vs. inoperative) | Same word as operose | Same word as opine |
| Same word as opinionated, opinionative, self-opinionated | Same word as opisthognathous (vs. prognathous) | Same word as opponent, opposing |
| Same word as opportune (vs. inopportune) | Same word as opportunist, opportunistic | Same word as oppose |
| Same word as opposed (vs. unopposed) | Same word as opposite | Same word as oppositive |
| Same word as oppress | Same word as oppressed | Same word as oppressive |
| Same word as opprobrious | Same word as oppugn | Same word as opsonize |
| Same word as opt out | Same word as optimistic | Same word as optimistic (vs. pessimistic) |
| Same word as optimize, optimise | Same word as optimize, optimise | Same word as optimum, optimal |
| Same word as optional (vs. obligatory) | Same word as opulent | Same word as oracular |
| Same word as oral | Same word as oral (vs. aboral) | Same word as orange, orangish |
| Same word as orange-brown | Same word as orange-colored, orange-coloured, orange-hued | Same word as orange-flowered |
| Same word as orange-red, orangish-red | Same word as orange-sized | Same word as orate |
| Same word as oratorical | Same word as orb, orbit, | Same word as orbicular |
| Same word as orbiculate, orbicular | Same word as orbitual | Same word as orchestrate |
| Same word as ordain | Same word as ordain,ordinate, order | Same word as order |
| Same word as ordered | Same word as ordered (vs. disordered) | Same word as orderly |
| Same word as ordinal (vs. cardinal) | Same word as ordinary | Same word as ordinary (vs. extraordinary) |
| Same word as ordinate | Same word as organic | Same word as organic (vs. inorganic) |
| Same word as organize, organise | Same word as organize, organise, orchestrate | Same word as organized (vs. disorganized) |
| Same word as organized (vs. unorganized) | Same word as organized, organised, | Same word as orgiastic |
| Same word as orient | Same word as orient, orientate | Same word as oriental |
| Same word as orientalize, orientalise | Same word as oriented (vs. unoriented), orientated | Same word as orienting (vs. disorienting), orientating |
| Same word as original | Same word as original | Same word as original (vs. unoriginal) |
| Same word as originate | Same word as originative | Same word as ornament |
| Same word as ornamental | Same word as ornate | Same word as ornery |
| Same word as orotund | Same word as orphan | Same word as orphaned |
| Same word as orthodox (vs. unorthodox) | Same word as orthogonal | Same word as orthomolecular |
| Same word as orthostatic | Same word as Oscan-speaking | Same word as oscillate |
| Same word as oscillate, vibrate | Same word as oscillatory, oscillating | Same word as oscitant |
| Same word as osculate | Same word as ossified | Same word as ossify |
| Same word as ostensible | Same word as ostensible, ostensive | Same word as ostensive |
| Same word as ostentate | Same word as ostentatious | Same word as ostracize, ostracise |
| Same word as otherwise | Same word as otherworldly | Same word as otiose |
| Same word as ototoxic | Same word as oval-bodied | Same word as oval-fruited |
| Same word as oval-shaped, ovate, oviform, ovoid, | Same word as ovate | Same word as oven |
| Same word as oven-ready | Same word as oven-shaped | Same word as ovenbake |
| Same word as over(predicate) | Same word as over-correct, overcompensate | Same word as over-embellished |
| Same word as over-the-counter, | Same word as over-the-counter, otc | Same word as over-the-top |
| Same word as overabundant | Same word as overachieve | Same word as overact,overplay |
| Same word as overactive | Same word as overage, overaged,over-the-hill | Same word as overall |
| Same word as overambitious | Same word as overanxious | Same word as overarch |
| Same word as overawe | Same word as overawed | Same word as overbalance |
| Same word as overbear | Same word as overbearing | Same word as overbid |
| Same word as overblown | Same word as overboil | Same word as overbold |
| Same word as overburden | Same word as overburdened | Same word as overbusy |
| Same word as overcapitalize, overcapitalise | Same word as overcareful | Same word as overcast |
| Same word as overcautious | Same word as overcharge | Same word as overcloud |
| Same word as overcome | Same word as overcompensate | Same word as overconfident |
| Same word as overcook | Same word as overcredulous | Same word as overcritical |
| Same word as overcrop, overcultivate | Same word as overcrowd | Same word as overcurious |
| Same word as overdelicate | Same word as overdo | Same word as overdone |
| Same word as overdone, overstated | Same word as overdose | Same word as overdramatize, overdramatise |
| Same word as overdraw | Same word as overdress | Same word as overdress, overclothe |
| Same word as overdressed | Same word as overdrive | Same word as overdue |
| Same word as overeager | Same word as overemotional | Same word as overemphasize, overemphasise, overstress |
| Same word as overenthusiastic | Same word as overestimate, overrate | Same word as overexcited |
| Same word as overexert | Same word as overexploit | Same word as overexpose |
| Same word as overfamiliar | Same word as overfed | Same word as overfeed |
| Same word as overfill | Same word as overflow | Same word as overflow, overrun |
| Same word as overflowing | Same word as overfly | Same word as overfond |
| Same word as overfull | Same word as overgeneralize, overgeneralise | Same word as overgreedy |
| Same word as overgrow | Same word as overgrown | Same word as overhand (vs. underhand), overhanded, overarm |
| Same word as overhand, oversewn | Same word as overhang | Same word as overhasty |
| Same word as overhaul, | Same word as overhear | Same word as overheat |
| Same word as overheated | Same word as overindulge,overgorge, overeat | Same word as overindulgent |
| Same word as overjealous | Same word as overjoy | Same word as overjoyed |
| Same word as overladen, overloaded | Same word as overland | Same word as overlap |
| Same word as overlarge | Same word as overleap | Same word as overlie |
| Same word as overlie, overlay | Same word as overload | Same word as overload,overcharge |
| Same word as overlook | Same word as overlook, overtop | Same word as overlooked |
| Same word as overlooking | Same word as overlying | Same word as overmodest |
| Same word as overmuch | Same word as overnice | Same word as overnight |
| Same word as overpay | Same word as overplay,overact | Same word as overpopulate |
| Same word as overpower, overmaster, overwhelm | Same word as overpowering, overwhelming | Same word as overpraise |
| Same word as overprice | Same word as overpriced | Same word as overprint |
| Same word as overproduce | Same word as overprotect | Same word as overprotective |
| Same word as overproud | Same word as overreach | Same word as overreaching |
| Same word as overreact | Same word as overrefine, over-refine | Same word as overrefined |
| Same word as override | Same word as overriding | Same word as overripe |
| Same word as overrule, overturn, override, overthrow | Same word as overrun | Same word as oversea |
| Same word as overseas | Same word as oversee | Same word as oversensitive |
| Same word as overserious | Same word as oversew | Same word as oversexed |
| Same word as overshadow | Same word as overshoot | Same word as overshot |
| Same word as oversimplify | Same word as oversize, oversized | Same word as oversolicitous |
| Same word as overspecialize, overspecialise | Same word as overspend | Same word as overspread |
| Same word as overstate | Same word as overstate,overdraw | Same word as overstay, outstay |
| Same word as overstep | Same word as overstock | Same word as overstrain, overextend |
| Same word as overstretch | Same word as overstrung | Same word as overstuff |
| Same word as overstuffed | Same word as oversubscribed | Same word as oversupply |
| Same word as oversuspicious | Same word as overt (vs. covert), open | Same word as overtake, overhaul |
| Same word as overtax | Same word as overthrow,overturn | Same word as overtire, overweary, overfatigue |
| Same word as overtrump | Same word as overturn | Same word as overturned |
| Same word as overuse, overdrive | Same word as overvaliant | Same word as overvalue, overestimate |
| Same word as overweening | Same word as overweight | Same word as overwhelm |
| Same word as overwhelm, overpower,overcome, overtake | Same word as overwhelming | Same word as overwinter |
| Same word as overwork | Same word as overwork, | Same word as overwrite |
| Same word as overwrought | Same word as overzealous | Same word as oviparous (vs. ovoviviparous) (vs. viviparous) |
| Same word as ovulate | Same word as owe | Same word as owing(predicate), |
| Same word as owlish | Same word as own up | Same word as own(prenominal) |
| Same word as owned (vs. unowned) | Same word as owner-occupied | Same word as ox-eyed |
| Same word as oxford-grey, oxford-gray | Same word as oxidative | Same word as oxidise, oxidize, oxidate |
| Same word as oxidizable | Same word as oxidize, oxidise, oxidate | Same word as oxidized, oxidised |
| Same word as oxygenate, oxygenize, oxygenise, | Same word as oxygenize, oxygenise | Same word as oyster |
| Same word as ozonize, ozonise |
