In linguistics
Linguistics is the scientific study of human language. Linguistics can be broadly broken into three categories or subfields of study: language form, language meaning, and language in context....

, the lexicon (or wordstock) of a language is its vocabulary
A person's vocabulary is the set of words within a language that are familiar to that person. A vocabulary usually develops with age, and serves as a useful and fundamental tool for communication and acquiring knowledge...

, including its words and expressions. A lexicon is also a synonym of the word thesaurus
A thesaurus is a reference work that lists words grouped together according to similarity of meaning , in contrast to a dictionary, which contains definitions and pronunciations...

. More formally, it is a language's inventory of lexeme
A lexeme 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...

s. Coined in English 1603, the word "lexicon" derives from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 "λεξικόν" (lexicon), neut. of "λεξικός" (lexikos), "of or for words", from "λέξις" (lexis), "speech", "word", and that from "λέγω" (lego), "to say", "to speak".

The lexicon includes the lexemes used to actualize words. Lexemes are formed according to morpho-syntactic
In linguistics, a morpheme is the smallest semantically meaningful unit in a language. The field of study dedicated to morphemes is called morphology. A morpheme is not identical to a word, and the principal difference between the two is that a morpheme may or may not stand alone, whereas a word,...

 rules and express sememe
A sememe is a semantic language unit of meaning, correlative to a morpheme.A sememe is a proposed unit of transmitted or intended meaning; it is atomic or indivisible. A sememe can be the meaning expressed by a morpheme, such as the English pluralizing morpheme -s, which carries the sememic...

s. In this sense, a lexicon organizes the mental
The concept of mind is understood in many different ways by many different traditions, ranging from panpsychism and animism to traditional and organized religious views, as well as secular and materialist philosophies. Most agree that minds are constituted by conscious experience and intelligent...

 vocabulary in a speaker's mind: First, it organizes the vocabulary of a language according to certain principles (for instance, all verbs of motion may be linked in a lexical network) and second, it contains a generative device producing (new) simple and complex words according to certain lexical rules. For example, the suffix '-able' can be added to transitive verb
Transitive verb
In syntax, a transitive verb is a verb that requires both a direct subject and one or more objects. The term is used to contrast intransitive verbs, which do not have objects.-Examples:Some examples of sentences with transitive verbs:...

s only, so that we get 'read-able' but not 'cry-able'.

Usually a lexicon is a container for words belonging to the same language. Some exceptions may be encountered for languages that are variants, like for instance Brazilian Portuguese
Brazilian Portuguese
Brazilian Portuguese is a group of Portuguese dialects written and spoken by most of the 190 million inhabitants of Brazil and by a few million Brazilian emigrants, mainly in the United States, United Kingdom, Portugal, Canada, Japan and Paraguay....

 compared to European Portuguese
European Portuguese
European Portuguese refers to the variety of Portuguese spoken in continental Portugal, as well as the Azores and Madeira islands...

, where a lot of words are common and where the differences may be marked word by word.

When linguists study the lexicon, they study such things as what words are, how the vocabulary in a language is structured, how people use and store words, how they learn words, the history and evolution of words (i.e. etymology
Etymology is the study of the history of words, their origins, and how their form and meaning have changed over time.For languages with a long written history, etymologists make use of texts in these languages and texts about the languages to gather knowledge about how words were used during...

), types of relationships between words as well as how words were created.

An individual's mental lexicon, lexical knowledge, or lexical concept is that person's knowledge of vocabulary
A person's vocabulary is the set of words within a language that are familiar to that person. A vocabulary usually develops with age, and serves as a useful and fundamental tool for communication and acquiring knowledge...

. The role the mental lexicon plays in speech perception and production, as well as questions of how words from the lexicon are accessed, is a major topic in the fields of psycholinguistics
Psycholinguistics or psychology of language is the study of the psychological and neurobiological factors that enable humans to acquire, use, comprehend and produce language. Initial forays into psycholinguistics were largely philosophical ventures, due mainly to a lack of cohesive data on how the...

 and neurolinguistics
Neurolinguistics is the study of the neural mechanisms in the human brain that control the comprehension, production, and acquisition of language. As an interdisciplinary field, neurolinguistics draws methodology and theory from fields such as neuroscience, linguistics, cognitive science,...

, where models such as the cohort model
Cohort model
The cohort model in psycholinguistics and neurolinguistics is a model of lexical retrieval first proposed by William Marslen-Wilson in the late 1980s. It attempts to describe how visual or auditory input is mapped onto a word in a hearer's lexicon...

 have been proposed to explain how words in the lexicon are retrieved.

See also

  • Glossary
    A glossary, also known as an idioticon, vocabulary, or clavis, is an alphabetical list of terms in a particular domain of knowledge with the definitions for those terms...

  • Lexical markup framework
    Lexical Markup Framework
    ISO 24613:2008, Language resource management - Lexical markup framework , is the ISO International Organization for Standardization ISO/TC37 standard for natural language processing and machine-readable dictionary lexicons...

  • Function word
    Function word
    Function words are words that have little lexical meaning or have ambiguous meaning, but instead serve to express grammatical relationships with other words within a sentence, or specify the attitude or mood of the speaker...

  • Morphology (linguistics)
    Morphology (linguistics)
    In linguistics, morphology is the identification, analysis and description, in a language, of the structure of morphemes and other linguistic units, such as words, affixes, parts of speech, intonation/stress, or implied context...

  • Lexicography
    Lexicography is divided into two related disciplines:*Practical lexicography is the art or craft of compiling, writing and editing dictionaries....

  • Lexicology
    Lexicology is the part of linguistics which studies words, their nature and meaning, words' elements, relations between words , word groups and the whole lexicon....

  • Idiolect
    In linguistics, an idiolect is a variety of a language unique to an individual. It is manifested by patterns of vocabulary or idiom selection , grammar, or pronunciations that are unique to the individual. Every individual's language production is in some sense unique...

Further reading

  • Aitchison, Jean
    Jean Aitchison
    Jean Aitchison is a Professor of Language and Communication in the Faculty of English Language and Literature at the University of Oxford and a Fellow of Worcester College, Oxford....

    . Words in the Mind: An Introduction to the Mental Lexicon. Malden, MA: Blackwell, 2003.
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