Inquiry. Query, interrogation, question, interrogatory; study, investigation, research, exploration, examination, scrutiny; asking, search.
Ant. Guess, intuition, conjecture, assumption, supposition, hypothesis.
Inquisitive. Curious, meddlesome, intrusive, searching, prying, inquiring, meddling, peeping, scrutinizing.
Ant. Uninterested, unconcerned, careless, heedless, apathetic, inattentive, indifferent.
Inroad. Incursion, foray, raid, irruption, encroachment, trespass, infringement, dragonnade.
Ant. Occupation, sally, retreat, settlement, evacuation, excursion, egress.
Insane. Crazy, lunatic, mad, deranged, demented, crazed, delirious.
Ant. Sane, sound, sensible, quiet, composed, sober.
Insanity. Delirium, dementia, frenzy, lunacy, mania, aberration, madness, alienation, derangement, monomania, hallucination, craziness.
Ant. Sanity, clearness, rationality, lucidity, good sense, reason, intellect, intelligence.