foreplay (n.)

by 1921 in sexual sense, from fore- + play (n.); Freud's Vorlust was translated earlier as fore-pleasure (Brill, 1910). A more direct translation from the German would be thwarted by the sense drift in English lust (n.). Earlier as a theatrical term:

In fact the poem which Mr. Brooks has translated is but the "prologue to the swelling theme," the fore-play to the actual drama of Faust. [The Christian Examiner and Religious Miscellany, Jan.-May 1857]