Definition of alternatim in US English:

alternatim

adverb

  • In church music: in a style which features two or more singers or groups of singers in turn, or which features the alternation of voices with the organ or other instruments.

adjective

  • Of church music or its performance: featuring two or more singers or groups of singers in turn, or the alternation of voices with the organ or other instruments.

Origin

Mid 16th century; earliest use found in Thomas Harding (1516–1572), theologian and religious controversialist. From classical Latin alternātim alternately from alternāt-, past participial stem of alternāre + -im, suffix forming adverbs.