utterly or obviously senseless, illogical, or untrue; contrary to all reason or common sense; laughably foolish or false

an absurd explanation.

the quality or condition of existing in a meaningless and irrational world.

adjective

certain , logical , rational , reasonable , sensible , wise

adjective

batty , campy , crazy , daffy , dippy , flaky * , fooling around , foolish , for grins , freaky , gagged up , goofy * , idiotic , illogical , inane , incongruous , irrational , jokey , joshing , laughable , loony , ludicrous , nonsensical , nutty , off the wall , preposterous , sappy * , screwy * , silly , stupid , tomfool , unreasonable , wacky , harebrained , imbecilic , insane , lunatic , mad , moronic , softheaded , unearthly , zany , ad absurdum , asinine , baroque , bizarre , chimerical , daedalic , egregious , fantastic , fatuous , funny , grotesque , impracticable , inconsistent , inept , infeasible , insuperable , kooky , laputan , macaronic , meaningless , paradox , reductio ad absurdum , ridiculous , senseless , unbelievable , unrealistic