King James Dictionary 
RELIG'IOUS, a. L. religiosus.
1. Pertaining or relating to religion as a religious society a religious sect a religious place religious subjects. 2. Pious godly loving and reverencing the Supreme Being and obeying his precepts as a religious man. 3. Devoted to the practice of religion as a religious life. 4. Teaching religion containing religious subject or the doctrines and precepts of religion, or the discussion of topics of religion as a religious book. 5. Exact strict such as religion requires as a religious observance of vows or promises. 6. Engaged by vows to a monastic life as a religious order or fraternity. 7. Appropriated to the performance of sacred or religious duties as a religious house.
RELIG'IOUS, n. A person bound by monastic vows, or sequestered from secular concerns and devoted to a life of piety and devotion a monk or friar a nun.
Vine's Expository Dictionary of NT Words 
"religious, careful of the externals of divine service," akin to threskeia (see above), is used in James 1:26 .
Acts 17:22Superstitious. Acts 13:43Devout
Webster's Dictionary 
(1): ( a.) Belonging to a religious order; bound by vows.
(2): ( n.) A person bound by monastic vows, or sequestered from secular concern, and devoted to a life of piety and religion; a monk or friar; a nun.
(3): ( a.) Of or pertaining to religion; concerned with religion; teaching, or setting forth, religion; set apart to religion; as, a religious society; a religious sect; a religious place; religious subjects, books, teachers, houses, wars.
(4): ( a.) Possessing, or conforming to, religion; pious; godly; as, a religious man, life, behavior, etc.
(5): ( a.) Scrupulously faithful or exact; strict.
Charles Buck Theological Dictionary 
In a general sense, something that relates to religion. It is also used for a person engaged by solemn vows to the monastic life; or a person shut up in a monastery, to lead a life of devotion and austerity under some rule or institution. The male religious are called monks and friars; the females, nuns and canonesses.
Cyclopedia of Biblical, Theological and Ecclesiastical Literature 
in a general sense, is something that relates to religion; and, in reference to persons, thatwhich indicates that they give their attention to religion, and are so influenced by it as to differ from the world. It was also applied to members of monastic orders. (See Religiosi).