Definitions of canonical:

• adjective:   conforming to orthodox or recognized rules

  Example: "The drinking of cocktails was as canonical a rite as the mixing- Sinclair Lewis"

• adjective:   of or relating to or required by canon law
• adjective:   appearing in a Biblical canon

  Example: "A canonical book of the Christian New Testament"

• adjective:   reduced to the simplest and most significant form possible without loss of generality

  Example: "A canonical syllable pattern"