oppressor, n. tyrant, persecutor, extortioner.

option, n. choice, preference, election, discretion, alternative.  Antonyms:  constraint, coercion, compulsion.

optional, a. discretional, elective.  Antonyms:  compulsory, coercive, obligatory.

oral, a. spoken, verbal, parole, vocal, nuncupative.

oration, n. declamation, rhetoric.

orator, n. declaimer, rhetorician.

oratorical, a. rhetorical, eloquent, declamatory.

ordeal, n. crucible.

order, n. mandate, command, precept, direction, decree, decretal, injunction; rule, regulation, law, canon, prescription; method, system, disposition, arrangement; succession, sequence; dictation, bidding, commission; grade, degree, class; tranquillity, quiet.

order, v. methodize, systematize, regulate; bid, command, dictate, enjoin.

ordering, n. distribution, disposition, regulation.

orderly, a. systematic, methodical, well-regulated, regular; peaceable.

ordinary, a. common, regular, conventional, commonplace, mediocre, average, usual.

organic, a. constitutional, vital, fundamental, essential, inherent, instrumental.

organization, n. organism; formation, construction, making.

organize, v. arrange, systematize, form.

orgies, n. pl. carousal, revels, debauch, wassail, saturnalia, bacchanals, riot.

origin, n. source, beginning, derivation, rise, origination.

original, a. first, primeval, aboriginal, primitive, archetypal, primordial, pristine; creative, productive, inventive, ingenious.  Antonyms:  derivative, copied.

original, n. origin, archetype, prototype, model, pattern.

Orkney Islands.  Associated Word:  Orcadian.

ornament, n. decoration, embellishment, adornment, garniture, ornamentation; parure.

ornament, v. decorate, embellish, garnish, bedeck, grace, beautify.

ornamental, a. embellishing, beautifying, garnishing.

ornamentation, n. adornment, garniture, embellishment; arabesque, moresque; purfling; fret-work.

ornate, a. ornamented, decorated, embellished, florid, adorned.

orthodox, a.  Antonym:  heterodox.

orthodoxy, n.  Antonym:  heterodoxy.

oscillate, v. fluctuate, vacillate.

ostentatious, a. showy, pompous, spectacular, gaudy, pretentious.

ounce by ounce. unciatim.

oust, v. eject, evict, dispossess, dislodge, remove, displace, expel, depose.

ousting, n. ejection, eviction, expulsion, dispossession, ouster, removal, disseizin, deposition.

out, adv. away, absent, abroad; outright, aloud, audibly; wanting, lacking, deficient in; extinguished; at variance.

out and out. wholly, completely, openly.—­a. absolute, unqualified, undisguised.

outbounds, n. pl. limits, boundaries, confines.