baseform

Base form, often called the lemma or dictionary form, is the canonical form of a word from which its inflected forms are derived. It serves as a representative form for a lexeme in linguistic analysis and dictionary entries. The base form is not always a single fixed surface form across languages, but it is the form used as the reference point for inflection, syntax, and meaning.

In English, the base form of a verb is the form used to express the verb without tense, aspect, or agreement inflection, and it is typically the form found in dictionaries. Examples include go, speak, and eat. For nouns, the base form is usually the singular form that appears in dictionaries, such as cat rather than cats. In languages with rich morphology, the base form acts as the starting point for generating all inflected variants.

In computational linguistics, the base form is central to lemmatization, the process of converting a word form to its base form or lemma. This contrasts with stemming, which trims forms without guaranteeing a valid word. Lemmatization supports tasks like information retrieval, search indexing, and text analysis by normalizing different inflections to a single representative form. For example, went becomes go, and cats become cat.

Limitations arise from irregular forms and polysemy. Some languages have multiple valid lemmas for a single surface form, and context may be required to select the appropriate base form. Nevertheless, the concept of a base form is a foundational tool in linguistics, lexicography, and natural language processing for organizing and analyzing word forms.