obdurate : stubborn
obese : fat
oblique : slanting; deviating from the perpendicular or from a straight line
obnoxious : offensive
obsequious :slavishly attentive; servile; sycophantic
obsolete : outmoded
obtrusive : pushing toward
obtuse : blunt; stupid
occult : mysterious; secret; supernatural
odious : hateful
odoriferous : giving off an order
odorous : having an odor
officious : meddlesome; excessively trying to please
olfactory : concerning the sense of smell
ominous : threatening
omnipotent : all-powerful
omniscient : all-knowing
omnivorous : eating both plant and animal food; devouring everything
onerous : burdensome
opalescent : iridescent
opaque : dark; not transparent
opportune : timely; well chosen
opprobrious : disgraceful
ornate : excessively decorated; highly decorated
ostensible : apparent; professed; pretended
ostentatious : showy; pretentious
