lemma
A proposition proved or accepted for immediate use in the proof of some other proposition.
Other meanings
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.
“Cat is a lemma, but cats is not.”
Word history
From Ancient Greek "λῆμμᾰ" (premise, assumption).
Where this comes from
This definition is adapted from “lemma” on Wiktionary, by its contributors, published under CC BY-SA 4.0. This page is published under the same licence.