Letter O

oaf - awkward person
obdurate - unyielding, hardhearted
obeisance - homage, deference
obelisk - tall column, monument
obese - fat
obfuscate - bewilder, muddle
obituary - eulogy
objective (adj.) - unbiased
objective (noun) - goal
objectivity - impartiality
oblation - offering, sacrifice
obligatory - required, compulsory
oblige - compel
obliging - accommodating, considerate
oblique - indirect
obliquity - perversity
obliterate - destroy
oblong - elliptical, oval
obloquy - slander
obscure - vague, unclear
obsequious - fawning, servile
obsequy - funeral ceremony
observant - watchful
obsolete - outdated
obstinate - stubborn
obstreperous - noisy, unruly
obtain - gain possession
obtrusive - forward, meddlesome
obtuse - stupid
obviate - make unnecessary
Occident - the West
occlude - block
occult - mystical, secret, relating to
the supernatural or witchcraft
octogenarian - person in her eighties
ocular - optic, visual
ode - poem
odious - despicable
odoriferous - pleasant odor
odyssey - journey
offal - inedible parts of a butchered
animal
offertory - church collection
officiate - supervise
officious - forward, obtrusive
offset - counterbalance
ogle - flirt
ogre - monster, demon
oleaginous - oily
oligarchy - aristocracy
olio - medley
ominous - threatening
omnibus - collection, compilation
omnipotent - all-powerful
omniscient - all-knowing
onerous - burdensome
onslaught - powerful attack
ontology - the study of the nature of
existence
onus - burden
opaque - nontransparent
operative - working
operetta - musical comedy
opiate - narcotic
opine - think, express an opinion
opportune - well-timed, appropriate
oppress - persecute
oppressive - burdensome
opprobrious - abusive, scornful
opprobrium - disgrace
oppugn - assail
opt - decide, choose
optimum - best condition
optional - elective
opulence - wealth
opus - literary work or musical
composition
oracle - prophet
oration - speech
orator - speaker
orb - sphere
orchestrate - organize
ordain - appoint
orderly - neat, arranged
ordinance - law
ordnance - artillery
orient - align, familiarize
orison - prayer
ornate - lavishly decorated
ornithology - study of birds
orthodox - conventional
oscillate - waver, swing
ossify - harden
ostensible - apparent, seeming
ostentatious - pretentious
ostracize - banish, shun
otherworldly - spiritual
otiose - idle
ouster - ejection
outmoded - out-of-date
outré - eccentric
outset - beginning
ovation - applause
overrule - disallow
overture - advance, proposal
overweening - arrogant, forward
overwhelm - overpower
overwrought - overworked, highstrung
ovum - egg, cell