O
obscure, difficult, and subtle
observation, discrimination, and comparison
obsolete, artificial, and inadequate
obstinacy, stupidity, and wilfulness
officious, fidgety, and talkative
old, absurd, and meaningless
one, individual, and integral
openly, frankly, and legitimately
opposition, bitterness, and defiance
oppressive, grasping, and slanderous
opulent, powerful, and prosperous
organization, monopoly, and pressure
origin, character, and aim
original, terse, and vigorous
overriding, arrogant, and quarrelsome