The Collaborative International Dictionary of English v.0.48:
canonic \ca*non"ic\ (k[.a]*n[o^]n"[i^]k), canonical
\ca*non"ic*al\ (k[.a]*n[o^]n"[i^]*kal), 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."
2. Appearing in a Biblical canon; as, a canonical book of the
Christian New Testament.
3. Accepted as authoritative; recognized.
4. (Math.) In its standard form, usually also the simplest
form; -- of an equation or coordinate.
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.
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,
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
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.