The entire office, or series of prayers and psalms said (or chanted) in the Roman Catholic Church — Vespers, Matins, Lauds and Mass — is called plenarium.
Some plenaria included all the writings of the New Testament, others those parts of the scriptures that were commonly read in the Mass and bore the name Lectionarium Plenarium (Becker, "Catal.
In monasteries, the use of several books for each service created no great problem; but priests who did not make the Benedictine religious profession of "stability, conversion of manners and obedience" and who travelled from place to place on their missionary duties, found it best to carry a single book with them, and the complete missal or Missale Plenarium came into use among them, especially after the foundation of the mendicant orders.
It contained all necessary prayers for the celebration of the Mass, which until then had to be taken from different books — the Sacramentary, Lectionary, Evangelistary, Antiphonary, and Gradual (Zaccaria, "Bibl.
In Germany, plenarium denoted a popular book that gave the German translation of the Epistles and Gospels for the Sundays and festivals of the entire liturgical year, together with a short exposition and instruction.