lemma

from The Century Dictionary.

• noun In logic:
• noun In the Stoical logic
• noun The major premise of a hypothetical syllogism, or modus ponens: thus, in the reasoning, “If it is day, it is light; but it is day: hence, it is light,” the first premise was called the lemma.
• noun A premise in general.
• noun A Megaric sophism depending on the question whether a man who says “I am lying” is truly lying or not.
• noun In mathematics, a proposition upon which it is necessary to arrest the attention for the sake of proving an ulterior one, but which interrupts the regular series of theorems; also, a premise drawn from another branch of mathematics than that under consideration.
• noun A theme; a thesis; the subject of an epigram, or of a musical composition, etc.
• noun In embryology, the primary or outer layer of the germinal vesicle. Pascoe.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Math., Logic) A preliminary or auxiliary proposition demonstrated or accepted for immediate use in the demonstration of some other proposition, as in mathematics or logic.
• noun A word that is included in a glossary or list of headwords; a headword.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun mathematics A proposition proved or accepted for immediate use in the proof of some other proposition.
• noun linguistics, usually The canonical form of an inflected word.
• noun linguistics, less frequently A lexeme; all the inflected forms of a term.
• noun botany One of the specialized bracts around the floret in grasses.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the lower and stouter of the two glumes immediately enclosing the floret in most Gramineae
• noun a subsidiary proposition that is assumed to be true in order to prove another proposition
• noun the heading that indicates the subject of an annotation or a literary composition or a dictionary entry