late 14c., from Old French expectant or directly from Latin expectantem/exspectantem (nominative expectans/exspectans), present participle of expectare/exspectare "await, desire, hope" (see expect). Meaning "pregnant" is by 1861. Related: Expectantly. As a noun, "one who waits in expectation," from 1620s.[expectant etymology, expectant origin, 英语词源]