Impostor
late 16th century (in early use spelled imposture, and sometimes confused with imposture in meaning): from French imposteur, from late Latin impostor, contraction of impositor, from Latin imponere (see impose).
wiktionary
From Middle French imposteur.
etymonline
impostor (n.)
1580s, "swindler, cheat," from French imposteur (16c.), from Late Latin impostor "a deceiver," agent noun from impostus, contraction of impositus, past participle of imponere "place upon, impose upon, deceive," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + ponere "to put, place" (past participle positus; see position (n.)). Meaning "one who passes himself off as another" is from 1620s. Related: Impostrous. For a fem. form, Bacon uses French-based impostress (1610s) while Fuller, the church historian, uses Latinate impostrix (1650s).
