Definition of lunatic :
1. A person affected by lunacy; an insane person, esp. one who has lucid intervals; a madman; a person of unsound mind.
2. Affected by lunacy; insane; mad.
3. Of or pertaining to, or suitable for, an insane person; evincing lunacy; as, lunatic gibberish; a lunatic asylum.
mental, weak-minded, harebrained, ruinous, simpleminded, non compos mentis, barmy, sane, loony, fool, cabbage, nutjob, fruity, asinine, swashbuckler, damaging, unearthly, oddball, unwise, nuts, daredevil, bats, absurd, softheaded, dotty, dopey, madcap, tomfool, buggy, loony tunes, crackers, touched, imbecile, dwarf, weirdie, wud, disastrous, harum-scarum, madwoman, wise, eccentric, hazardous, bananas, loco, knowledge, brainsick, cuckoo, perilous, backward, scatty, half-baked, unhinged, imbecilic, haywire, bughouse, risky, weirdo, unsafe, cockeyed, disordered, brainless, daffy, off, silly, nonsensical, cripple, hothead, fire-eater, hunchback, wrong, gaga, foolish, crackbrained, loon, screwball, sappy, dingbat, lunkheaded, wacko, headcase, bubbleheaded, featherheaded, oddity, witless, cranky, dippy, wacky, preposterous, certifiable, crazed, inept, balmy, humpback, screwy, bonkers, moonstruck, harmful, senseless, moronic, loopy, half-witted, zany, meshuga, space cadet, ding-a-ling, unsound, distraught, bedlam, mentally ill, fatuous, jerky, injurious, cracked, dangerous, ability
foolish (part of speech: adjective)
lunatic (part of speech: noun)
insane (part of speech: adjective)
demented, maniacal, irrational, feverish, babbling, kooky, hysterical, deranged, crack-brained, brain-sick, psychotic, nutty, mad, unbalanced, berserk, crazy, frenzied, delirious, neurotic, schizoid, psycho, blithering, batty, insane
- The Mayor looked at Phil as if he were looking at a lunatic, then he smiled and started in to fill up a cheque. - "The Spoilers of the Valley", Robert Watson.
- Free to starve with this pauper lunatic? - "What Maisie Knew", Henry James.
- " Oh, he's out of a lunatic asylum," Captain Rames almost groaned aloud. - "The Turnstile", A. E. W. (Alfred Edward Woodley) Mason.