Open English Wordnet
Nouns
(n)Improperium(usually plural) one of a series of antiphons and responses expressing the remonstrance of Jesus Christ with his people, usually sung on Good Friday.“In their present form in the Roman Rite, the Improperia are a series of three couplets, sung antiphonally by cantors and followed by alternate Greek and Latin responses from the two halves of the choir; and nine other lines sung by the cantors, with the full choir responding after each with the refrain "Popule meus, quid feci tibi? . . . ."”