What does antiphonal mean?
The definition of antiphonal
An*tiph”o*nal, a.
Of or pertaining to antiphony, or alternate singing; sung alternately by a divided choir or opposite choirs. Wheatly.

— An*tiph”o*nal*ly, adv.

An*tiph”o*nal, n.
A book of antiphons or anthems.