Thesaurus

Synonyms for Whacky include:

absurd, amok, amuck, around the bend, asinine, balmy, barmy, bats, batty, berserk, bonkers, brainsick, buggy, certifiable, certified, cockamamie, cockamamy, cockeyed, crackbrained, cracked, crackers, crazed, crazy, daft, demented, demoniac, demoniacal, deranged, derisory, distracted, disturbed, dotty, fatuous, fey, fond, foolish, fruity, goofy, half-crazed, harebrained, haywire, hebephrenic, idiotic, ill-advised, ill-conceived, impolitic, imprudent, inadvisable, inane, insane, irrational, kookie, kooky, laughable, loco, loony, loopy, ludicrous, lunatic, mad, maniac, maniacal, manic-depressive, maniclike, mentally ill, mindless, misguided, moonstruck, non compos mentis, nonsensical, nuts, nutty, of unsound mind, paranoid, possessed, preposterous, psychopathic, psychopathologic, psychopathological, psychotic, rattlebrained, rattlepated, raving, raving mad, ridiculous, round the bend, sappy, scatterbrained, scatty, schizophrenic, screw-loose, screwy, sick, silly, touched, unadvisable, unadvised, unbalanced, unhinged, unreasonable, unsound, unstable, unwise, vacuous, wacky, whacky, wild, zany

whacky is a ADJ.