O

obduracy of mind [obduracy = intractable; hardened]

object of contempt

obligation of loyalty

obliquity of vision [obliquity = mental deviation or aberration]

obscurity of twilight

ocean of eloquence

omission of fact

onrush of life

onsets of temptation

openness of mind

opulence of detail

orgy of lying

ornaments of eloquence

outbreak of hostilities

outburst of tears

outflow of sympathy

outposts of morality

overflow of vitality