canonical (Adjective) — Appearing in a biblical canon. ex. "a canonical book of the Christian New Testament"
canonical (Adjective) — Of or relating to or required by canon law.
canonical (Adjective) — Reduced to the simplest and most significant form possible without loss of generality. ex. "a canonical syllable pattern"
canonical (Adjective) — Conforming to orthodox or recognized rules. ex. "the drinking of cocktails was as canonical a rite as the mixing"