What is the meaning of Friar?

A brother or member of any religious order, but especially of one of the four mendicant orders, viz: (a) Minors, Gray Friars, or Franciscans. (b) Augustines. (c) Dominicans or Black Friars. (d) White Friars or Carmelites. See these names in the Vocabulary.

Source: Webster’s Revised Unabridged Dictionary (1913), via OPTED