1610s, "insufficient," from French incompétent, from Late Latin incompetentem (nominative incompetens) "insufficient," from in- "not" (see in- (1)) + Latin competentem (see competent). Sense of "lacking qualification or ability" first recorded 1630s. The noun meaning "incompetent person" is from 1866. Related: Incompetently.[incompetent etymology, incompetent origin, 英语词源]