Differences between a 'monk' and a 'friar'?

Q. What’s the difference between a monk and a friar?

A. Though the term monk is commonly used to designate all male religious, it more properly refers to a member of a community of men that leads a more or less contemplative life apart from the world, under vows of poverty, chastity, and obedience, according to a formal rule. Monks tend to remain living in one place (Benedictines actually take a fourth vow of “stability”), and they chant in choir the Divine Office of daily prayer. The English word monk comes ultimately from the Greek monos, meaning “solitary” or “alone.” Some examples of monastic communities would be the Benedictines, the Cistercians, and the Carthusians.

Friars (literally, “brothers”) are also male religious who live in community under a formal rule; like monks, they pray the Divine Office in choir. But they aren’t properly called “monks” because their work of preaching, going out among those in the world, soliciting alms, and moving from place to place isn’t consistent with the monastic ideal.

While the vow of poverty for monks allows the community to own property corporately, originally the friars were allowed neither individual nor corporate ownership of property; they had no fixed revenues to live on and relied totally on the voluntary offerings of the faithful. This restriction (which was eventually modified) meant that begging for alms was an important part of their activity; that’s why they also came to be called mendicants (literally, “beggars”). Some examples of friars would be the Dominicans and the Franciscans.

A Catholic Dictionary (ed., Donald Attwater; 3rd ed., Macmillan, 1958) provides this useful comparison:

“‘Friar’ is not synonymous with ‘monk’; they are as different as artillery from infantry; the life of a monk is normally passed within the walls of his monastery; a friar has his headquarters in a friary but his work is of the active ministry and may take him to all parts of the earth; a friar is a member of a highly organized, widespread body with a central authority to which he is professed; a monk’s allegiance is to the abbot of an autonomous individual monastery.”

We should also note that clerics (or clerks) regular form a third class of male religious. Though they too are bodies of men in the Church bound by solemn religious vows and living in a religious community under a rule, they’re engaged primarily in the active work of priestly ministry. Unlike the monks and mendicants, they aren’t expected to pray the Daily Office in choir. The Jesuits, the Theatines, and the Barnabites are three examples of clerics regular.