In the lexicon of certain branches of Christianity, especially the Roman Catholic, Anglican, and Orthodox branches, religious as a noun usually refers to a member of a religious institute of monks, nuns, friars, clerics regular, or to another individual who takes the three vows of poverty, chastity, and obedience (the evangelical counsels) in a religious institute.
Catholic canon law definition 
Religious are members of religious institutes, societies in which the members take public vows and live a fraternal life in common. This is a form of consecrated life distinct from other forms, such as that of secular institutes. It is distinct also from forms that do not involve membership of an institute, such as that of consecrated hermits, that of consecrated virgins, and other forms whose approval is reserved to the Holy See.
Clerical or lay 
If religious have been ordained as deacons, priests or bishops, they belong to the clergy and are referred to as the "religious clergy", a term that distinguishes them from the clergy who have not taken religious vows and who are known as the secular clergy or, since they generally serve under a bishop who exercises governance over a geographically defined diocese, as the diocesan clergy. The other religious are lay people, not members of the clergy.
While the state of consecrated life is neither clerical or lay, institutes themselves are classified as one or the other, a clerical institute being one that "by reason of the purpose or design intended by the founder or by virtue of legitimate tradition, is under the direction of clerics, assumes the exercise of sacred orders, and is recognized as such by the authority of the Church".
Canon law 
The Code of Canon Law devotes to religious 103 canons arranged in eight chapters:
- Religious houses and their erection and suppression
- The governance of institutes
- The admission of candidates and the formation of members
- The obligations and rights of institutes and their members
- The apostolate of institutes
- Separation of members from the institute
- Religious raised to the episcopate
- Conferences of major superiors
See also 
- Consecrated life
- Institute of consecrated life
- Religious institute
- Religious congregations
- Secular institute
- Society of apostolic life
- Code of Canon Law, canon 607
- Code of Canon Law, canon 710
- Code of Canon Law, canon 603
- Code of Canon Law, canon 604
- Code of Canon Law, canon 605
- Cf. Code of Canon Law, canon 207
- Code of Canon Law, canon 588
- Code of Canon Law, canons 607 to 709