Difficult GRE Words - Group 8

omnivorous:
a. eating both plant and animal food; devouring everything; having interest in a variety of subjects

on track:
a. proceeding as planned, as expected, or in a manner consistent with an established pattern

onerous:
a. burdensome or oppressive; not easily borne; wearing

onlooker:
n. one that looks on; spectator

onslaught:
n. violent attack; sudden and severe onset of trouble

onus:
n. burden or obligation; difficult or disagreeable responsibility or necessity

opalescent:
a. varying in color when seen in different lights or from different angles; lustrous

opaque:
a. impenetrable by light; not transparent; not reflecting light; having no luster

opiate:
n. medicine to induce sleep or deaden pain; something that relieves emotions or causes inaction

opprobrious:
a. bringing disgrace; shameful or infamous

opulence:
n. extreme wealth; luxuriousness; abundance

oracular:
a. prophetic; uttered as if with divine authority; mysterious or ambiguous

oration:
n. elaborate discourse; delivered in public; treating an important subject in a formal and dignified manner

oratorio:
n. musical composition for voices and orchestra based on religious text

oratory:
n. place of orisons, or prayer; chapel or small room set apart for private devotions

ordain:
v. decree or command; grant holy orders; predestine

ordination:
n. act of admitting to holy orders; disposition as in ranks or rows; formal arrangement

ornithology:
n. branch of zoology that deals with the study of birds

oscillate:
v. swing back and forth with a steady, uninterrupted rhythm; vibrate pendulum like; waver

ossify:
v. change or form into bone; become set in a rigidly conventional pattern; change from soft tissue to hard bony tissue