lemma

A proposition proved or accepted for immediate use in the proof of some other proposition.

A proposition originally used for such a purpose, but having later acquired a greater, independent, importance; a fundamental (often pithy) and widely-used result.

The canonical form of an inflected word; i.e., the form usually found as the headword in a dictionary, such as the nominative singular of a noun, the bare infinitive of a verb, etc.

The theoretical abstract conceptual form of a word, representing a specific meaning, before the creation of a specific phonological form as the sounds of a lexeme, which may find representation in a specific written form as a dictionary or lexicographic word.