Relating to or consisting of antiphons; performed by means of alternating responses or voices.
From antiphon + -ic (relating to). The -ic suffix is a common way to form adjectives from nouns in technical and musical terminology.
Antiphonic singing in churches created an early form of stereo sound—two groups singing from opposite sides meant you'd hear different musical lines from different directions, which must have seemed almost magical in dim medieval churches.
Complete word intelligence in one call. Free tier — 50 lookups/day.