Origin: 1375–1425; (v.) late Middle English purporten < Anglo-French purporter to convey, equivalent to pur-pro-1 + porter to carry (< Latin portāre); (noun) late Middle English < Anglo-French, derivative of the v.
1422, from Anglo-Fr. purport (1278), from purporter "to contain," from pur- (from L. pro- "forth") + O.Fr. porter "to carry," from L. portare "to carry" (see port (1)). The verb is attested from 1528. Purportedly "allegedly" first recorded 1949.