Thesaurus

Synonyms for Unreasonable include:

abnormal, absurd, all-fired, amok, amuck, around the bend, balmy, barmy, bats, batty, berserk, blind, bonkers, brainsick, buggy, certifiable, certified, counterintuitive, crackbrained, cracked, crackers, crazed, crazy, daft, demented, demoniac, demoniacal, deranged, distracted, disturbed, dotty, exaggerated, excessive, exorbitant, extortionate, extraordinary, extreme, extremist, far, fey, fruity, half-crazed, haywire, hebephrenic, idiotic, illogical, immoderate, incoherent, inconsequential, indefensible, inordinate, insane, intemperate, intense, intuitive, irrational, kookie, kooky, loco, loony, loopy, lunatic, mad, maniac, maniacal, manic-depressive, maniclike, mentally ill, mindless, moonstruck, non compos mentis, nonrational, nuts, nutty, of unsound mind, outrageous, over-the-top, overdone, overstated, paranoid, possessed, psychopathic, psychopathologic, psychopathological, psychotic, radical, raving, raving mad, reasonless, round the bend, schizophrenic, screw-loose, screwy, senseless, sick, sinful, stark, steep, superstitious, touched, ultra, unbalanced, unconscionable, undue, unhinged, unjustified, unlogical, unreasonable, unreasoning, unsound, unstable, untenable, unwarranted, usurious, visceral, wacky, whacky, wild

unreasonable is a ADJ.