Definition of "lemma" [lem•ma]

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

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "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."