Definitions
from The American Heritage® Dictionary of the English Language, 4th Edition
 n. A subsidiary proposition assumed to be valid and used to demonstrate a principal proposition.
 n. A theme, argument, or subject indicated in a title.
 n. A word or phrase treated in a glossary or similar listing.
 n. The outer or lower of the two bracts that enclose the flower in a grass spikelet.
from Wiktionary, Creative Commons Attribution/ShareAlike License
 n. A proposition proved or accepted for immediate use in the proof of some other proposition.
 n. The canonical form of an inflected word.
 n. A lexeme; all the inflected forms of a term.
 n. One of the specialized bracts around the floret in grasses.
from the GNU version of the Collaborative International Dictionary of English
 n. A preliminary or auxiliary proposition demonstrated or accepted for immediate use in the demonstration of some other proposition, as in mathematics or logic.
 n. A word that is included in a glossary or list of headwords; a headword.
from The Century Dictionary and Cyclopedia
 n. In logic:
 n. In the Stoical logic
 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.
 n. A premise in general.
 n. A Megaric sophism depending on the question whether a man who says “I am lying” is truly lying or not.
 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.
 n. A theme; a thesis; the subject of an epigram, or of a musical composition, etc.
 n. In embryology, the primary or outer layer of the germinal vesicle. Pascoe.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
 n. the lower and stouter of the two glumes immediately enclosing the floret in most Gramineae
 n. a subsidiary proposition that is assumed to be true in order to prove another proposition
 n. the heading that indicates the subject of an annotation or a literary composition or a dictionary entry
Etymologies
from The American Heritage® Dictionary of the English Language, 4th Edition
from Wiktionary, Creative Commons Attribution/ShareAlike License
Examples

Obviously, such a number would be far too large to manipulate readily, so, using a formula familiar to statisticians, it was normalized to produce a simple decimal number of only a few digits which I called the lemma's Exposure Index.

Emblem included a motto, called lemma, an image, and an epigram.

When no manuscripts are specified for the lemma in an entry, the lemma is the reading for those manuscripts not otherwise specified.

(A lemma is the word under which a set of related dictionary or encyclopedia entries appears.)

The short article discussion started in a wideranging discussion at not include what Chris and I have called the "lemma" problem because we didn't a good handle, and Larry wanted an actionable proposal.

For the latter, the "lemma" idea is still soft and in need of refinement; remember that this is a proposal that will produce instructions for the general CZ user.

"lemma" idea is still soft and in need of refinement; remember that this is a proposal that will produce instructions for the general CZ user.

Is there something wrong with a world in which everybody does lemmalemmatheoremappendix work?

The detail of the inconsistencies in the etymological treatment and in the alloseme/lemma status of the quintile and sextile that you mention is no less diabolical!

The florets are enclosed by other specialized bracts (the lemma and palea).
biocon commented on the word lemma
In addition, lemma means 1. the husk or shell of a fruit; 2. the lower bract of a floret of a grass; 3. the external layer of the germinal vesicle (Oxford English Dictionary). Moreover, lemma signifies the external covering of an anatomical or biological structure. Examples are plasmalemma, the plasma membrane of any cell, and sarcolemma, the outer membrane of a myocyte (cell of a muscle).
July 1, 2011
reesetee commented on the word lemma
Wouldn't that be a dilemma?
*dodges tomatoes*
February 6, 2010
john commented on the word lemma
Plural of lemming.
February 5, 2010
sionnach commented on the word lemma
Jane Austen's little known contribution to the discipline of Logic.
February 8, 2008