The term Clerics Regular (previously Clerks Regular) designates a number of Catholic priests (clerics) who are members of a religious order (regular) of priests, but are not Canons Regular. Clerics regular differ from canons regular in that they do not possess cathedral or collegiate churches; they devote themselves more completely to pastoral care, in place of an obligation to the Liturgy of the Hours in common, and have fewer penitential observances in their Rule of Life.
By clerics regular are meant those bodies of men in the Church who while being essentially clerics, devoted to the exercise of the ministry in preaching, the administration of the sacraments, the education of youth, and other spiritual and corporal works of mercy, are at the same time religious in the strictest sense of the word, and living a community life according to a rule approved by the Holy See.
In the Corpus Juris Canonici the term "clerics regular" is often used for canons regular, and regular clerics are classed by authors as a branch or modern adaptation of the family of Canons Regular. This is because of the intimate connection existing between the two; for while separated from the secular clergy by their vows and the observance of a community life and a rule, they form a distinct class in the religious state, the clerical, in opposition to the monastic, which includes monks, and hermits.
Clerics regular are distinguished from the purely monastic bodies, or monks, in four ways:
They are distinguished from the friars in this, that though the latter are devoted to the sacred ministry and the cultivation of learning, they are not primarily priests.