GRE Essential Vocabulary – List O

Oafish- coarse, lubberly, stupid, boorish
Obdurate- stubborn, adamant, stiff-necked, mulish
Opp: malleable
Obeisance- curtsy, kow tow, salaam, adoration
Obfuscate- complicate, blur, befog, muddle
Opp: clarify
Obliterate- annihilate, expunge, eradicate, demolish
Oblivious- unconcerned, deaf, blind, handicap
Opp: conscious
Obnoxious- repulsive, loathsome, unsavory, yucky
Opp: delightful
Obscurity- oblivion, limbo, enigma, twilight
Opp: clarity
Obsequious- bootlicking, groveling, fawning, smarmy
Obsessive- neurotic, consuming, fanatical, tormenting
Obstinacy- tenacity, pertinacity, stubbornness, intransigence
Obtrusive- noticeable, conspicuous, prominent
Opp: inconspicuous
Obtuse- dumb headed, moronic, insensitive, cretinism
Opp: clever
Obviate- preclude, eliminate, prevent, unnecessary
Obstreperous- mutinous, raucous, clamorous, stroppy
Opp: restrained
Occult- diabolism, necromancy, cabalistic, arcane
Odious- sickening, abhorrent, repugnant, atrocious
Opp: delightful
Odyssey- crusade, wandering, peregrination, pilgrimage
Ogle- stare at, leer at
Ominous- sinister, portentous, baleful, gloomy
Opp: promising
Opine- reckon, suggest, presume, remark
Oppress- subjugate, dampen, tyrannize, maltreat
Opprobrium- obloquy, derogation, excoriation, ignominy
Opp: honor
Orgy- carousal, bender, surfeit, revelry
Ornate- flashy, orotund, overwrought, embellished
Opp: plain
Orthodox- conformist, conservative, observant, devout
Opp: unconventional
Ossify- fossilize, stagnate, solidify, petrify
Ostensible- alleged, purported, apparent, professed
Opp: genuine
Ostentatious- flamboyant, glitzy, extravagant, conspicuous
Opp: restrained
Ostracism- avoidance, shunning, spurning, rejection
Oust- expel, dislodge, boot out, depose
Outlandish- bizarre, freaky, eccentric, queer
Opp: ordinary
Overhaul- renovate, outstrip, service, mend
Overrate- overestimate, attach too much, think highly
Opp: underestimate
Overt- manifest, unconcealed, blatant, patent
Opp: covert
Overture- preliminary, approach, prelude
Overwhelm- trounce, inundate, devastate, triumph