In linguistics, conjugation () is the creation of derived forms of a verb from its principal parts by inflection (alteration of form according to rules of grammar). Conjugation may be affected by person, number, gender, tense, aspect, mood, voice, or other grammatical categories. Typically the principal parts are the root and/or several modifications of it (stems). All the different forms of the same verb constitute a lexeme, and the canonical form of the verb that is conventionally used to represent that lexeme (as seen in dictionary entries) is called a lemma.