imposterous

From impostor +‎ -ous.

imposterous (comparative more imposterous, superlative most imposterous)

1. (obsolete) fraudulent; pretending to be someone else
   • 1606, Francis Beaumont, John Fletcher, “The Woman-Hater”, in Comedies and Tragedies […], London: […] Humphrey Robinson, […], and for Humphrey Moseley […], published 1679, →OCLC, (please specify the act number in uppercase Roman numerals, and the scene number in lowercase Roman numerals):

     Twice have I seen her with thee , twice my thoughts Were prompted by mine eye to hold thy strictness False and imposterous

• outpromises