Synonym word of most unreasonable:

absurd, all wet, arbitrary, biased, capricious, contradictory, erratic, fallacious, far-fetched, foolish, full of hot air, headstrong, illogical, incoherent, incongruous, inconsequential, inconsistent, invalid, irrational, loose, mad, nonsensical, off the wall, opinionated, preposterous, quirky, reasonless, senseless, silly, stupid, thoughtless, unreasoned, vacant, wrong