“canonical: Characteristic or most frequent, either in a particular language of across languages in general. Thus a canonical form of words or syllables is a phonological pattern to which they typically conform; a canonical clause, as defined e.g. by Huddleston and Pullum CGEL, is declarative and active, as opposed to a ‘non-canonical’ interrogative or passive.
Also in the sense of ‘simplest’ or ‘most straightforward.’ Thus a pattern e.g. of ‘one form one meaning’ might be called ‘canonical’ in that the description of other patterns is more complex.”
Excerpted from: Matthews, P.H., ed. The Oxford Concise Dictionary of Linguistics. New York: Oxford University Press, 2014.