Headword

A headword is the word that forms the label at the top of an entry in a dictionary, glossary, or other language reference work. It is the form under which all inflected or derived forms are organized and cited, and it is typically the form used for alphabetical sorting within the resource.

In lexicography, the headword often corresponds to the lemma or base form of a set of related word forms. The lemma is the canonical form chosen for citation, while the headword is the form that appears as the entry heading. In many languages, especially those with rich morphology, the headword is the lemma, but some dictionaries may use a different entry form depending on editorial conventions.

Headwords are usually written in standard orthography and may reflect capitalization rules for proper nouns. Multiword headwords—such as "United States" or "look up"—are treated as single entries for indexing purposes, often with sorting rules that consider the first component. In bilingual or multilingual dictionaries, the headword may identify the source-language form or the target-language equivalent, depending on the entry’s orientation.

The headword functions as the anchor for the entry’s content, including senses, pronunciations, part of speech, etymology, usage notes, and example sentences. In computational linguistics and information retrieval, headwords serve as index terms and search anchors, enabling efficient retrieval of related inflected forms and related senses.

Example: the headword run has inflected forms such as runs, ran, running, and runny as a related form; the entry for run would catalog its senses and grammatical information under that headword.