Charles Buck Theological Dictionary 
Something belonging to monks, or the monkish life.
The monastic profession is a kind of civil death, which in all worldly matters has the same effect with the natural death. The council of Trent, &c. fix sixteen years the age at which a person may be admitted into the monastical state. St. Anthony is the person who, in the fourth century, first instituted the monastic life; as St. Pachomius, in the same century, is said to have first set on foot the coenobite life, 1: e. regular communities of religious. In a short time the deserts of Egypt became inhabited by a set of solitaries, who took upon them the monastic profession. St. Basil carried the monkish humour into the East, where he composed a rule which afterwards obtained through a great part of the West. In the eleventh century, the monastic discipline was grown very remiss. St. Oddo first began to retrieve it in the monastery of Cluny: that monastery, by the conditions of its erection, was put under the immediate protection of the holy see; with a prohibition to all powers, both secular and ecclesiastical, to disturb the monks in the possession of their effects or the election of their abbot. In virtue hereof they pleaded an exemption from the jurisdiction of the bishop, and extended this privilege to all the houses dependent on Cluny. This made the first congregation of several houses under one chief immediately subject to the pope, so as to constitute one body, or as they now call it, one religious order. Till then, each monastery was independent, and subject to the bishop.
Webster's Dictionary 
(1): ( n.) A monk.
(2): ( a.) Alt. of Monastical