Webster's Revised Unabridged Dictionary · 1913

main entry word

main entry word , noun

The form of a word that heads a lexical entry and is alphabetized in a dictionary; also called entry word, headword, and lemma.

In different languages, different wordforms, such as cases for verbs, may be taken as the main entry word. In English dictionaries, it is the infinitive form, but in latin dictionaries it is usually the first person singular present.