Anacronym

Definition: An acronym whose etymonic origin is either not known to, or irrelevant to and forgotten by, most speakers; the word therefore stands on its own with identity as a full-fledged word and not solely an acronym despite acronymic etymology, and (in the strongest cases, including laser, radar, sonar, lidar, and scuba) usually takes lowercased styling (because to capitalize it would represent undue emphasis on its etymonic origin).