antiphon (n.)

c. 1500, "a versicle sung responsively," from French antiphone "hymn" or directly from Medieval Latin antiphona, from Greek antiphona (neuter plural), from antiphonos "responsive, sounding in answer," from anti "in return" (see anti-) + phōnē "voice," from PIE root *bha- (2) "to speak, tell, say."

A reborrowing by English of the word which had become anthem in English (in Old English antefn, antifon) and lost its original meaning.