From (still dialectally attested) kļūdīt, originally the iterative form of kļūt (“to become”) (q.v.), with the meaning “to reach, to get (somewhere),” later “to reach accidentally, by mistake”, “to get lost,” and then “to make a mistake” (a meaning still found in its surviving reflexive form kļūdīties). The corresponding noun kļūda probably evolved from “chance, accident” to “misfortune” and finally “mistake.” Cognates include Lithuanian kliàuda (“lack, blame, defect”).