partofspeech

Part of speech is a category used in grammar to group words by their syntactic function and morphological behavior. Traditional grammars divide words into classes such as noun, verb, adjective, adverb, pronoun, determiner (including articles and demonstratives), preposition, conjunction, and interjection. Some languages also recognize numerals, classifiers, or particles as separate categories. In English, common parts of speech are noun, pronoun, verb, adjective, adverb, determiner, preposition, conjunction, and interjection, though many words can serve more than one function.

A word's part of speech is determined by how it behaves in sentences, what it combines with, and how it inflects. For example, run can be a noun (a long run) or a verb (to run); quickly is an adverb describing how an action is performed; the and a are determiners that mark noun phrases; and and, but are conjunctions joining clauses.

Parts of speech are useful for describing syntax, teaching language, and processing text. In linguistics, POS tagging assigns a word its likely category in context, which can be challenging due to multifunctional words and context-dependent meanings. In computational linguistics, POS information serves as a feature for parsing, tokenization, and grammar checking.

Notable variations exist across languages: some have rich inflectional morphology that marks case or tense on the word, while others rely more on word order. Understanding parts of speech provides a foundation for sentence structure and meaning.