An Historical and Comparative Encyclopaedia of Chinese Conceptual Schemes
General Editor: Christoph Harbsmeier 何莫邪; Associate Editor: Jiang Shaoyu 蔣紹愚
1. a Lexeme Representation identifying a morpheme in the language, pronunciation, and graphs used for the morpheme
2. a Synonym Group identifying a meta-linguistically well-defined general meanings of that morpheme
Lexemes are unspecified as to syntactic function, and also with respect to general semantic features such as "plural" or "generic".
Whether a given meaning of a word is to be classified under one given Lexeme or another is often a matter of arbitrary organisation and convenience.
For example, one might say that Teach is simply the causative of Learn because to teach is to try to cause someone to learn. Moreover, in many cases causatives like "blacken" are entered not in a separate Synonym Group, but simply as a causative usage under Black. The decision to establish a separate Synonym Group and Lexeme for "to teach" is a matter of convenience rather than of pure logic: the Synonym Group "TEACH" is deemed to be of greater interest to us than the entirely predictable Synonym Group "BLACKEN".