Responsorii, Psalmi

Responsorii, Psalmi mean either the repetition of the verses by the people, or the repetition of the last words of the psalm, with the addition of the "amen" or the doxology; or that the psalms were so selected as to correspond to the subject of the lessons which had been read. — Eadie, Eccles. Cyclop. s.v. "Psalmody."