obsession.noun
compulsive-preoccupation with a fixed idea or an unwanted feeling or emotion, often accompanied by symptoms of anxiety; a compulsive, often unreasonable idea or emotion
obsessional.adjective
obsessionally.adverb

offhand, offhandedly.adverb
without preparation or forethought; extemporaneously
offhanded.adjective
performed or expressed without preparation or forethought; extemporaneous
offhandedness.noun

on the one hand.idiom
as one point of view; from one standpoint
on the other hand
as another point of view; from another standpoint

oblique.adjective
indirect or evasive (oblique political maneuvers); devious, misleading, or dishonest (gave oblique reasoning in his efforts to prove the evolutionary theory); not direct in descent; having a slanting or sloping direction, course, or position; inclined; Mathematics-–-designating geometric lines or planes that are neither parallel nor perpendicular
obliquely.adverb
obliqueness.noun

open-minded.adjective
having or showing receptiveness to new and different ideas or the opinions of others; broadminded
openmindedly.adverb
openmindedness.noun

obscene.adjective
offensive to accepted standards of decency or modesty; coarse; incitinglustful feelings; lewd; offensive or repulsive to the senses; loathsome
obscenely.adverb
obscenity.noun, plural-obscenities
the state or quality of being obscene; indecency, lewdness, or offensiveness in behavior, expression, or appearance; something, such as a word, an act, or an expression, that is indecent or lewd; something that is offensive or repulsive to the senses ("what had once been a gentle hill covered with lush grass turned into a brown obscenity of bare earth and smoke" ...Tom Clancy)

obsequious.adjective
full of or exhibiting servile.compliance; fawning (the waiter must have come from a slave camp or perhaps needed a tip so bad; he was so spinlessly and sugary obsequious {'yes sir, no sir, whatever you want or say sir'}); the flunkies that sop up popular opinions without question
obsequiously.adverb
obsequiousness.noun

osteomalacia.noun
a disease occurring mostly in adult women that results from a deficiency in vitamin D or calcium and is characterized by a softening of the bones with accompanying pain and weakness
osteoporosis.noun,.noun.plural-osteoporoses
a disease in which the bones become extremely porous, are subject to fracture and heal slowly, occurring especially in women following menopause and often leading to curvature of the spine from vertebral collapse
osteoporotic.adjective

outmoded.adjective
not in fashion; unfashionable (outmoded attire); outmoded ideas; no longer usable or practical; obsolete-(outmoded machinery)
outmode, outmoded, outmoding,outmodes.transitive verbs-
to cause to become unfashionable or obsolete

orgasm.noun
the highest point of sexual excitement, characterized by strong feelings of pleasure and marked normally by ejaculation of semen by the male and by vaginal contractions in the female; also called climax; a similar point of intensity of emotional excitement
orgasmic or orgastic.adjective
orgasmically or orgastically.adverb

ostensive.adjective
seeming or professed; ostensible
ostensively.adverb

ostensible.adjective
represented or appearing as such; ostensive.(the ostensible purpose was charity, but his real goal was popularity)
ostensibly.adverb

obdurate.adjective
hardened in wrongdoing or wickedness; stubbornly impenitent; hardened against feeling; hardhearted; not giving in to persuasion; intractable; inflexible
obdurately.adverb
obdurateness.noun

obsolete.adjective
no longer in use (an obsolete word); old; outmoded in design, style, or construction (an obsolete locomotive)
obsolete, obsoleted, obsoleting, obsoletes.transitive verbs-
to cause to become obsolete; to fall into disuse; obsolescent
obsoletely.adverb
obsoleteness, obsoletism.nouns

ooze1, oozed, oozing, oozes.verbs
intransitive use-to flow or leak out slowly, as through small openings; to disappear or ebb slowly; (his courage oozed away); to progress slowly but steadily; to exude moisture; to emit a particular essence or quality (the house oozed with charm)
transitive use-to give off; exude; to emit or radiate in abundance (he oozes confidence)
ooze.noun
the act of oozing; something that oozes
ooze2.noun
soft mud or slime; a layer of mudlike sediment on the floor of oceans and lakes, composed chiefly of remains of microscopic sea animals; muddy ground

overriding, overridingly.adjective
first in priority; more important than all others (our overriding concern is the eradication of illiteracy)
override, overrode, overridden, overriding, overrides.transitive verbs-
to ride across; to ride beyond; to trample on; to ride (a horse) too hard; to prevail over; conquer (budgetary concerns overrode all other considerations); to declare null and void; set aside (congress overrode the President's veto); to counteract the normal operation of (an automatic control); to extend over; overlap
override, overrider.nouns

override.noun
a sales commission collected by an executive in addition to the commission received by a subordinate salesperson; royalty; a mechanism or system used to counteract an automatic control; the act or an instance of nullifying

obloquy.noun, plural.obloquies
abusively detractive language or utterance; calumny; the condition of disgrace suffered as a result of abuse or vilification; ill repute; disgrace

orchestrate, orchestrated, orchestrating, orchestrates.transitive verbs
to arrange or control the elements of, as to achieve a desired overall effect (orchestrated the building of a large boat) orchestrator.noun
Music.-.to compose or arrange music for performance by an orchestra

opulence.also.opulency.noun
wealth; affluence; great abundance; profusion
opulent.adjective
possessing or exhibiting great wealth; affluent; characterized by rich abundance; luxuriant
opulently.adverb