Please find below a list of O adjectives which might be used to describe a person.
Positive
omniscient
optimistic
outstanding
overjoyed
Negative
oblivious
obnoxious
obscene
obsessive
obstinate
odd
offbeat
offensive
onerous
ornery
overaggressive
overbearing
overconfident
Other
obedient
obese
objective
oily
old
older
oldest
olivefaced
opinionated
opportunistic
ordinary
outgoing
outlandish
outraged
outspoken
overactive
overcerebral
overcurious
overeager
overgenerous
overjoyed
overprotective
There are many more lists of adjectives on this website. For more adjectives starting in O, see this post containing a large number of adjectives beginning with the letter O, some of which can be used for describing people.
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