lemma

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A subsidiary proposition assumed to be valid and used to demonstrate a principal proposition.
2. n. A theme, argument, or subject indicated in a title.
3. n. A word or phrase treated in a glossary or similar listing.
4. n. The outer or lower of the two bracts that enclose the flower in a grass spikelet.

Century Dictionary and Cyclopedia

1. n. In logic:
2. n. In the Stoical logic
3. n. 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.
4. n. A premise in general.
5. n. A Megaric sophism depending on the question whether a man who says “I am lying” is truly lying or not.
6. n. 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.
7. n. A theme; a thesis; the subject of an epigram, or of a musical composition, etc.
8. n. In embryology, the primary or outer layer of the germinal vesicle. Pascoe. Synonyms See inference.

Wiktionary

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

GNU Webster's 1913

1. n. (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.
2. n. A word that is included in a glossary or list of headwords; a headword.

WordNet 3.0

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