Lexical category
In [[grammar]], a '''lexical category''' (also '''word class''', '''lexical class''', or in traditional grammar '''part of speech''') is a linguistic category of words (or more precisely ''lexical items''), which is generally defined by the [[syntactic]] or [[morphology (linguistics)|morphological]] behaviour of the lexical item in question. Common linguistic categories include ''noun'' and ''verb'', among others. There are [[open class word|open word classes]], which constantly acquire new members, and [[closed class word|closed word classes]], which acquire new members infrequently if at all.

Different languages may have different lexical categories, or they might associate different properties to the same one. For example, [[Japanese language|Japanese]] has at least three classes of adjectives{{Fact|date=July 2008}} where English has one; Chinese and Japanese have [[measure word]]s while European languages have nothing resembling them; many languages don't have a distinction between adjectives and adverbs, or adjectives and nouns{{Fact|date=September 2007}}, etc. Many linguists argue that the formal distinctions between parts of speech must be made within the framework of a specific language or language family, and should not be carried over to other languages or language families.

==History==
The classification of words into lexical categories is found from the earliest moments in the [[history of linguistics]].<ref>Robins, R. H. (1989). ''General Linguistics''. 4th ed. London: Longman.</ref> In the ''[[Nirukta]]'', written in the [[5th century BCE|5th]] or [[6th century BCE]], the [[Sanskrit grammarian]] [[Yāska]] defined four main categories of words :<ref name=Matilal>
{{cite book |
author = [[Bimal Krishna Matilal]] |
title = The word and the world: India's contribution to the study of language |
publisher = Oxford. Yaska is dealt with in Chapter 3| 
year = 1990 |
}}</ref>
# nāma - [[noun]]s or substantives
# ākhyāta - [[verb]]s
# upasarga - pre-verbs or [[prefix]]es
# nipāta - [[Grammatical particle|particle]]s, invariant words (perhaps [[prepositions]])

These four were grouped into two large classes: [[inflection|inflected]] (nouns and verbs) and uninflected (pre-verbs and particles).

A century or two later, the [[Classical Greece|Greek]] scholar [[Plato]] wrote in the [[Cratylus (dialogue)|''Cratylus'' dialog]] that "... sentences are, I conceive, a combination of verbs [''rhēma''] and nouns [''ónoma'']".<ref>Cratylus 431b</ref> Another class, "conjunctions" (covering [[Grammatical conjunction|conjunction]]s, [[pronoun]]s, and the [[article (grammar)|article]]), was later added by [[Aristotle]].

By the end of the [[2nd century BCE]], the classification scheme had been expanded into eight categories, seen in the ''[[Art of Grammar|Tékhnē grammatiké]]'':

# Noun: a part of speech inflected for case, signifying a concrete or abstract entity
# Verb: a part of speech without case inflection, but inflected for tense, person and number, signifying an activity or process performed or undergone
# Participle: a part of speech sharing the features of the verb and the noun
# Article: a part of speech inflected for case and preposed or postposed to nouns (the relative pronoun is meant by the postposed article)
# Pronoun: a part of speech substitutable for a noun and marked for person
# Preposition: a part of speech placed before other words in composition and in syntax 
# Adverb: a part of speech without inflection, in modification of or in addition to a verb
# Conjunction: a part of speech binding together the discourse and filling gaps in its interpretation

The [[Latin grammar]]ian [[Priscian]] ([[floruit|fl.]] [[500 CE]]) modified the above eight-fold system, substituting "[[interjection]]" for "article". It wasn't until 1767 that the [[adjective]] was taken as a separate class.<ref>Beauzée, Nicolas, ''Grammaire générale, ou exposition raisonnée des éléments nécessaires du langage''. (Paris, 1767).</ref>

Traditional English grammar is patterned after the European tradition above, and is still taught in schools and used in [[dictionaries]]. It names eight parts of speech: [[noun]], [[verb]], [[adjective]], [[adverb]], [[pronoun]], [[preposition]], [[Grammatical conjunction|conjunction]], and [[interjection]] (sometimes called an exclamation).

==Controversies==
Since the Greek grammarians of 2nd century BCE, parts of speech have been defined by [[morphology (linguistics)|morphological]], [[syntax|syntactic]] and [[semantics|semantic]] criteria. However, there is currently no generally agreed-upon classification scheme that can apply to all languages, or even a set of criteria upon which such a scheme should be based.

Linguists recognize that the above list of eight word classes is simplified and artificial.<ref>Zwicky, Arnold (2006). ''What part of speech is "the"?'' Some would label "the" as an adjective because it tells "which one" about the noun that follows it.  By doing so, the word "the" is modifying the noun and, thus, it is quite adjectival. [[Language Log]].</ref> For example, "adverb" is to some extent a catch-all class that includes words with many different functions. Some have even argued that the most basic of category distinctions, that of nouns and verbs, is unfounded,<ref>Hopper, P. and S. Thompson. 1985. "The Iconicity of the Universal Categories 'Noun' and 'Verbs'". In ''Typological Studies in Language: Iconicity and Syntax.'' John Haiman (ed), vol. 6, pp. 151-183, Amsterdam: John Benjamins Publishing Company</ref> or not applicable to certain languages.<ref>Broschart, Jürgen 1997. "Why Tongan does it differently: Categorial Distinctions in a Language without Nouns and Verbs." ''Linguistic Typology'' 1(2):123-165.</ref>

==Functional classification==
Common ways of delimiting words by function include:
* '''[[Open word classes]]:'''
**[[adjective]]s
**[[adverb]]s 
**[[interjection]]s
**[[noun]]s
**[[verb]]s (except [[auxiliary verb]]s)

* '''[[Closed word classes]]:'''
**[[auxiliary verb]]s
**[[clitic]]s
**[[coverb]]s
**[[Grammatical conjunction|conjunction]]s
**[[determiner (class)|Determiner]]s ([[article (grammar)|article]]s, [[quantifier]]s, [[demonstrative adjective]]s, and [[possessive adjective]]s)
**[[grammatical particle|particle]]s
**[[measure word]]s
**[[adposition]]s (prepositions, postpositions, and circumpositions)
**[[preverb]]s
**[[pronoun]]s
**[[Contraction (grammar)|contraction]]s
**[[Names of numbers in English#Cardinal numbers|cardinal numbers]]

==English==
[[English language|English]] frequently does not [[marker (linguistics)|mark]] words as belonging to one part of speech or another. Words like ''neigh'', ''break'', ''outlaw'', ''laser'', ''microwave'' and ''telephone'' might all be either verb forms or nouns. Although ''-ly'' is an adverb marker, not all adverbs end in ''-ly'' and not all words ending in ''-ly'' are adverbs.  For instance, ''tomorrow'', ''slow'', ''fast'', ''crosswise'' can all be adverbs, while ''early'', ''friendly'', ''ugly'' are all adjectives (though ''early'' can also function as an adverb).

In certain circumstances, even words with primarily grammatical functions can be used as verbs or nouns, as in "We must look to the ''hows'' and not just the ''whys''" or "Miranda was ''to-ing and fro-ing'' and not paying attention".

==See also==
* [[Grammatical category]]
* [[Part-of-speech tagging]]
* [[Quirky subject]]
* [[Syntactic category]]

==References==
<references/>

==External links==
{{Wiktionary|part of speech}}
*[http://www.arts.uottawa.ca/writcent/hypergrammar/partsp.html The parts of speech]
*[http://www.kwiznet.com/p/takeQuiz.php?ChapterID=1860&CurriculumID=13 Parts of Speech Quiz]
*[http://www.quia.com/jg/65832.html Parts of Speech Activities at Quia]
*[http://grammar.ccc.commnet.edu/grammar/  Guide to Grammar and Writing]
*[http://email.eva.mpg.de/~haspelmt/2001wcl.pdf Martin Haspelmath. 2001. "Word classes/parts of speech." In: Baltes, Paul B. & Smelser, Neil J. (eds.) ''International Encyclopedia of the Social and Behavioral Sciences''. Amsterdam: Pergamon, 16538-16545.] (PDF)

[[Category:Grammar]]
[[Category:Parts of speech|!]]

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