Antiphon

From the Greek words anti, meaning "against," and phone, meaning "sound." An antiphon is literally a song sung back and forth by two choirs, or by one choir divided into two sections. In some Anglican Churches, the Kyrie and the Sursum Corda are two examples of antiphons. The familiar exchange "The Lord be with you" - "And also with you" (or in more formal forms "And with thy spirit") is also an antiphon.