loony

• POS: Adjective, Noun
• HYPHEN: loon=y

CIDE DICTIONARY

loony, a. [Shortened fr. lunatic.].

•  Crazy; insane; lunatic; mentally unsound.  [1913 Webster]
•  Very foolish; very impractical; as, loony ideas.  [PJC]

loony, n. 

 someone mentally deranged and possibly dangerous.  [WordNet 1.5]

OXFORD DICTIONARY

loony, n. & adj. sl.
--n. (pl. -ies) a mad or silly person; a lunatic.
--adj. (loonier, looniest) crazy, silly.

Idiom

loony-bin sl. a mental home or hospital.

Derivative

looniness n.

Etymology

abbr. of LUNATIC

THESAURUS

loony

absurd, apish, asinine, balmy, bananas, barmy, bats, batty, beany, bedlamite, befooled, beguiled, besotted, bonkers, brainless, buffoonish, buggy, bughouse, bugs, cockeyed, crackers, crazy, credulous, cuckoo, daffy, daft, dazed, dement, dippy, dizzy, doting, dotty, dumb, fatuitous, fatuous, flaky, flipped, fond, fool, foolheaded, foolish, freaked-out, fruitcakey, fruity, fuddled, futile, gaga, goofy, gulled, harebrained, haywire, idiotic, imbecile, inane, inept, infatuated, insane, just plain nuts, kooky, loon, loopy, mad, madman, maniac, maudlin, moronic, non compos, nut, nuts, nutty, off the hinges, off the track, off the wall, potty, preposterous, round the bend, sappy, screwball, screwballs, screwy, senseless, sentimental, silly, slaphappy, stupid, thoughtless, wacky, wet, witless

ROGET THESAURUS

loony

Insanity

N insanity, disordered reason, disordered intellect, diseased mind, unsound mind, abnormal mind, derangement, unsoundness, psychosis, neurosis, cognitive disorder, affective disorder, insanity, lunacy, madness, mania, rabies, furor, mental alienation, aberration, paranoia, schizophrenia, dementation, dementia, demency, phrenitis, phrensy, frenzy, raving, incoherence, wandering, delirium, calenture of the brain, delusion, hallucination, lycanthropy, brain storm, vertigo, dizziness, swimming, sunstroke, coup de soleil, siriasis, fanaticism, infatuation, craze, oddity, eccentricity, twist, monomania (caprice), kleptodipsomania, hypochondriasis, melancholia, depression, clinical depression, severe depression, hysteria, amentia, screw loose, tile loose, slate loose, bee in one's bonnet, rats in the upper story, dotage, insane, mad, lunatic, loony, crazy, crazed, aliene, non compos mentis, not right, cracked, touched, bereft of reason, all possessed, unhinged, unsettled in one's mind, insensate, reasonless, beside oneself, demented, daft, phrenzied, frenzied, frenetic, possessed, possessed with a devil, deranged, maddened, moonstruck, shatterpated, mad-brained, scatter brained, shatter brained, crackbrained, touched, tetched, off one's head, maniacal, delirious, lightheaded, incoherent, rambling, doting, wandering, frantic, raving, stark staring mad, stark raving mad, wild-eyed, berserk, delusional, hallucinatory, corybantic, dithyrambic, rabid, giddy, vertiginous, wild, haggard, mazed, flighty, distracted, distraught, depressed, agitated, hyped up, bewildered, mad as a March hare, mad as a hatter, of unsound mind, touched in one's head, wrong in one's head, not right in one's head, not in one's right mind, not right in one's wits, upper story, out of one's mind, out of one's wits, out of one's skull, far gone, out of one's senses, out of one's wits, not in one's right mind, fanatical, infatuated, odd, eccentric, hypped, hyppish, spaced out, imbecile, silly, like one possessed, the mind having lost its balance, the reason under a cloud, tet exaltee, tet montee, ira furor brevis est, omnes stultos insanire.