hindsightly adjective 1adverb 1forms 2 adjective1 •(nonstandard, rare) Of or pertaining to hindsight; retrospective.This can't happen all at once, says the nasty piece of perk, the old Houyhnhnm is hindsightly. — 1996 adverb1 •(nonstandard, rare) Retrospectively; in retrospect.My thought process was similar to the theory, but when I realized it, I was hindsightly biased. — 2011 formsmore hindsightly · most hindsightly