A lexeme ( pronunciation (helpinfo)) is an abstract unit of morphological analysis in linguistics that roughly corresponds to a set of forms taken by a single word. For example in the English language run runs ran and running are forms of the same lexeme conventionally written as RUN.1 A related concept is the lemma (or citation form) which is a particular form of a lexeme that is chosen by convention to represent a canonical form of a lexeme. Lemmas are used in dictionaries as the headwords and other forms of a lexeme are often listed later in the entry if they are not common conjugations of that word.

A lexeme belongs to a particular syntactic category has a certain meaning (semantic value) and in inflecting languages has a corresponding inflectional paradigm; that is a lexeme in many languages will have many different forms. For example the lexeme RUN has a present third person singular form runs a present non-third-person singular form run (which also functions as the past participle and non-finite form) a past form ran and a present participle running. (It does not include runner runners runnable etc.) The use of the forms of a lexeme is governed by rules of grammar; in the case of English verbs such as RUN these include subject-verb agreement and compound tense rules which determine which form of a verb can be used in a given sentence.

A lexicon consists of lexemes.

In many formal theories of language lexemes have subcategorization frames to account for the number and types of complements they occur with in sentences and other syntactic structures.

The notion of a lexeme is very central to morphology and thus many other notions can be defined in terms of it. For example the difference between inflection and derivation can be stated in terms of lexemes: Inflectional rules relate a lexeme to its forms. Derivational rules relate a lexeme to another lexeme. Decomposition

With languages whose orthography employs an alphabet its Lexemes are often composed of smaller units with individual meaning called morphemes according to root morpheme + derivational morphemes + desinence (not necessarily in this order) where: The root morpheme is the primary lexical unit of a word which carries the most significant aspects of semantic content and cannot be reduced to smaller constituents.2 The derivational morphemes carry only derivational information.3 The desinence is composed of all inflectional morphemes and carries only inflectional information.4

The compound root morpheme + derivational morphemes is often called the stem.5 The decomposition stem + desinence can then be used to study inflection. See also Look up lexeme in Wiktionary the free dictionary. Ending (linguistics) Inflection Lexical unit Lexical word vs. grammatical word Lexicography Lexis (linguistics) Marker (linguistics) Morpheme Morphology (linguistics) Multiword expression Null morpheme Root (linguistics) Stem Notes RUN is here intended to display in small caps. Software limitations may result in its display either in full-sized capitals (RUN) or in full-sized capitals of a smaller font; either is anyway regarded as an acceptable substitute for genuine small caps. SIL dictionary of linguistic terms: What is a root SIL dictionary of linguistic terms: What is a derivational affix SIL dictionary of linguistic terms: What is an inflectional affix SIL dictionary of linguistic terms: What is a stem v d eLexicography Types of reference works Dictionary  Glossary  Lexicon  Thesaurus Types of dictionaries Bilingual  Biographical  Conceptual  Defining  Electronic  Encyclopedic  Language for specific purposes dictionary  Machine-readable  Maximizing  Medical  Minimizing  Monolingual learner's  Multi-field  Phonetic  Picture  Reverse  Rhyming  Rime  Single-field  Specialized  Sub-field  Visual Lexicographic projects Lexigraf  WordNet Other List of lexicographers  List of online dictionaries v d eLexicology Major terms Lexicon  Idiolect  Word  Lexis  Lexical unit Elements Morpheme  Grapheme  Glyphs  Phoneme  Sememe  Seme  Lexeme  Lemma  Meronymy  Chereme Semantic relations Holonymy  Hyponymy  Troponymy  Idiom  Synonym  Antonymy  Lexical semantics  Semantic net Fonctions Function word  Headword Fields Morphology  Controlled vocabulary  English lexicology and lexicography  Lexicographic error  Lexicographic information cost  Linguistic prescription  Specialised lexicography  International scientific vocabulary