Lemma
Lemma (lem"mȧ) , noun
[Latin lemma, Greek lh^mma anything received, an assumption or premise taken for granted, from lamba`nein to take, assume. Compare Syllable.]
1.
(Mathematics, Logic) A preliminary or auxiliary proposition demonstrated or accepted for immediate use in the demonstration of some other proposition, as in mathematics or logic.
2.
A word that is included in a glossary or list of headwords; a headword.