OFFERTORY (from the ecclesiastical Lat. ofcrtorium, Fr. offcrloire, a place to which offerings were brought), the alms of a congregation collected in church, or at any religious service. Offertory has also a special sense in the services of both the English and Roman churches. It forms in both that part of the Communion service appointed to be said or sung, during the collection of alms, before the elements are consecrated. In music, an offertory is the vocal or instrumental setting of the offertory sentences, or a short instrumental piece played by the organist while the collection is being made.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)