Verbinflection

Verbinflection, or verb inflection, is the set of morphologically conditioned variants of a verb used to express grammatical information. It encodes categories such as tense, aspect, mood, voice, person, and number, and, in some languages, agreement with the subject or object. Inflected forms can be finite, used in clauses, or non-finite, used in non-clausal contexts (infinitives, participles, gerunds). Inflection contrasts with derivation, which creates new words or parts of speech rather than marking grammatical categories.

Morphology of verb inflection is typically realized through affixes (prefixes, suffixes, infixes), internal stem changes, or a combination of both. In analytic or periphrastic systems, auxiliary words and fixed word order carry much of the information that otherwise would be expressed by inflection. Inflectional patterns vary widely across languages, yielding a typological spectrum from highly fusional languages, where a single affix may encode multiple grammatical features, to agglutinative languages, where a sequence of distinct morphemes encodes each category, to isolating languages, which rely more on syntax and independent words.

Common inflectional categories include tense (past, present, future), aspect (perfective, imperfective), mood (indicative, subjunctive, imperative), voice (active, passive, middle), and agreement in person and number with the subject. Some verbs exhibit irregular or suppletive inflection or stem alternations that affect vowels or consonants. The scope and complexity of verb inflection influence verb forms, syntax, and, in many languages, word order.

Examples illustrate diversity: English marks past tense with -ed and present participles with -ing; Spanish conjugates for person and number across tenses; Turkish uses a chain of suffixes to encode tense, mood, aspect, person, and negation.