n,
nonagenarian.

old-time, a. late, former, quondam.

old woman. beldame, crone, gammer; witch, hag, harridan.

old-womanish, a. anile.

old-womanishness, n. anility.

omen, n. foretoken, sign, augury, portent, presage, prognostic,
auspice.

ominous, a. portentous, monitory, premonitory, threatening.

omission, n. default, oversight, neglect, pretermission, omittance,
non-performance.

omit, v. leave out, slap, pretermit, disregard, neglect, overlook,
ignore, delete.

omittance, n. omission, forbearance, default, neglect, oversight.

omnipresence, n. ubiquity.

omnipresent, n. ubiquitous.

one, n. unit. Associated Words: unify, unity, unification,
numerary.

one after the other. _seriatim_; tandem; alternately, consecutively.

one hundred years. century, centenary. Associated Words:
centenarian, centennial.

one letter. Associated Word: uniliteral.

on end. erect, perpendicular, upright.

oneness, n. unity, singleness, individuality, unanimity.

onerous, a. laborious, difficult, arduous.

one-sided, a. unilateral; partial, unfair, inequitable, _ex parte_.

one year. Associated Words: annual, annually.

on horseback. mounted.

onion, n. (that does not bottom out) scallion, eschallot, shallot.
Associated Words: alliaceous, cepaceous, leek, allium, garlic.

onlooker, n. looker-on, bystander, spectator, beholder, witness,
eye-witness.

on tap. broached, abroached.

on the sly. (Collog.) sly, covertly, furtively, clandestinely,
surreptitiously, secretly.

ooze, v. filter, exude, percolate, transude, seep.

oozing, n. percolation, filtering, exudation, distillation,
transudation.

opalescence, n. iridescence.

opalescent, a. iridescent.

opaque, a. intransparent; (Colloq.) obscure, unintelligible.

open, a. accessible, clear, unobstructed, unrestricted; ajar,
unlocked; extended, expanded, spread, gaping, yawning, unfolded,
dehiscent; frank, unreserved, candid, ingenuous, guileless, overt,
undisguised; generous, liberal, bounteous, open-handed; revealed, patent,
manifest; unsettled, undetermined, debatable, undecided, controvertible;
mild, clement; free, disengaged, unappropriated, unemployed.

open, v. spread, expand, unfold, evolve; reveal, disclose; unclose,
unlock, unfasten; begin, commence; dehisce.

open-air, a. outdoor, al-fresco.

opening, a. beginning, introductory, initiatory, preliminary.

opening, n. aperture, fissure, gap, orifice, rift, chasm, hiatus,
rent; begin