'Absurd' meant 'out of tune' — from Latin 'surdus' (deaf). Discordant music became anything jarring to reason.
Wildly unreasonable, illogical, or inappropriate; ridiculously incongruous.
From French 'absurde,' from Latin 'absurdus' (out of tune, discordant, ridiculous), from 'ab-' (away from, off) + 'surdus' (deaf, dull, mute, insensible). The original Latin sense was musical: something 'away from hearing,' meaning discordant or jarring to the ear, like a note that clashes with the harmony. From there it broadened to mean anything that clashes with reason or sense. Latin 'surdus' may derive from PIE