The popular name for the document called a "commendatory letter," obtaining for a priest admission to the celebration of the eucharist in a church other than the one to which he is attached. By means of these letters the competent superior bears witness to the bearer's legitimate ordination to the priesthood, his good moral standing in his own diocese or religious group, his freedom from any ecclesiastical penalty that excludes the celebration of the eucharist, his freedom from any irregularity, and his consequent commendable status in general. Since the beginning of the Church, clerics traveling for one purpose or another were furnished with such introductory letters. These ensured their hospitable reception in other places and enabled them to exercise their respective orders. Various names have been used for these documents: "letters," "canonical letters," and "testimonial letters"; but the most commonly used term was "commendatory letters." The term celebret, a Latin word meaning "let him celebrate," has been commonly used since the latter part of the 19th century. The exact origin of this term is not determinable. It may have been taken from the primary purpose of commendatory letters, namely, the admission of the bearer to the celebration of Mass. The earliest legislation concerning commendatory letters appeared in the 4th century, implying that they were used to some extent before that time. The present Church law concerning the celebret is found in canon 903 of the 1983 Code of Canon Law.
[g. f. schorr/eds.]
"Celebret." New Catholic Encyclopedia. . Encyclopedia.com. (January 22, 2019). https://www.encyclopedia.com/religion/encyclopedias-almanacs-transcripts-and-maps/celebret
"Celebret." New Catholic Encyclopedia. . Retrieved January 22, 2019 from Encyclopedia.com: https://www.encyclopedia.com/religion/encyclopedias-almanacs-transcripts-and-maps/celebret