{ } a. [ L. canonicus, LL. canonicalis, fr. L. canon: cf. F. canonique. See canon. ] Of or pertaining to a canon; established by, or according to, a canon or canons. “The oath of canonical obedience.” Hallam. [ 1913 Webster ]

2. Appearing in a Biblical canon; as, a canonical book of the Christian New Testament. [ PJC ]

3. Accepted as authoritative; recognized. [ PJC ]

4. (Math.) In its standard form, usually also the simplest form; -- of an equation or coordinate. [ PJC ]

5. (Linguistics) Reduced to the simplest and most significant form possible without loss of generality; as, a canonical syllable pattern. Opposite of nonstandard.
Syn. -- standard. [ WordNet 1.5 ]

6. Pertaining to or resembling a musical canon. [ PJC ]

Canonical books, or
Canonical Scriptures, those books which are declared by the canons of the church to be of divine inspiration; -- called collectively the canon. The Roman Catholic Church holds as canonical several books which Protestants reject as apocryphal. --
Canonical epistles, an appellation given to the epistles called also general or catholic. See Catholic epistles, under Canholic. --
Canonical form (Math.), the simples or most symmetrical form to which all functions of the same class can be reduced without lose of generality. --
Canonical hours, certain stated times of the day, fixed by ecclesiastical laws, and appropriated to the offices of prayer and devotion; also, certain portions of the Breviary, to be used at stated hours of the day. In England, this name is also given to the hours from 8 a. m. to 3 p. m. (formerly 8 a. m. to 12 m.) before and after which marriage can not be legally performed in any parish church. --
Canonical letters, letters of several kinds, formerly given by a bishop to traveling clergymen or laymen, to show that they were entitled to receive the communion, and to distinguish them from heretics. --
Canonical life, the method or rule of living prescribed by the ancient clergy who lived in community; a course of living prescribed for the clergy, less rigid than the monastic, and more restrained that the secular. --
Canonical obedience, submission to the canons of a church, especially the submission of the inferior clergy to their bishops, and of other religious orders to their superiors. --
Canonical punishments, such as the church may inflict, as excommunication, degradation, penance, etc. --
Canonical sins (Anc. Church.), those for which capital punishment or public penance decreed by the canon was inflicted, as idolatry, murder, adultery, heresy. [ 1913 Webster ]

adv. In a canonical manner; according to the canons. [ 1913 Webster ]

n. The quality of being canonical; canonicity. Bp. Burnet. [ 1913 Webster ]

n. pl. The dress prescribed by canon{ 2 } to be worn by a clergyman when officiating. Sometimes, any distinctive professional dress. [ 1913 Webster ]

Full canonicals, the complete costume of an officiating clergyman or ecclesiastic.

n. [ LL. canonucatus canonical: cf. F. canonicat. ] The office of a canon; a canonry. [ 1913 Webster ]

n. [ Cf. F. canonicité. ] The state or quality of being canonical; agreement with the canon. [ 1913 Webster ]