A syntactic category is either a phrasal category, such as noun phrase

Noun phrase

In grammar, a noun phrase, nominal phrase, or nominal group is a phrase based on a noun, pronoun, or other noun-like word optionally accompanied by modifiers such as adjectives....

or verb phrase

Verb phrase

In linguistics, a verb phrase or VP is a syntactic unit composed of at least one verb and the dependents of that verb. One can distinguish between two types of VPs, finite VPs and non-finite VPs . While phrase structure grammars acknowledge both, dependency grammars reject the existence of a...

, which can be decomposed into smaller syntactic categories, or a lexical category

Lexical category

In grammar, a part of speech is a linguistic category of words , which is generally defined by the syntactic or morphological behaviour of the lexical item in question. Common linguistic categories include noun and verb, among others...

, such as noun

Noun

In linguistics, a noun is a member of a large, open lexical category whose members can occur as the main word in the subject of a clause, the object of a verb, or the object of a preposition .Lexical categories are defined in terms of how their members combine with other kinds of...

or verb

Verb

A verb, from the Latin verbum meaning word, is a word that in syntax conveys an action , or a state of being . In the usual description of English, the basic form, with or without the particle to, is the infinitive...

, which cannot be further decomposed.

The three criteria used in defining syntactic categories are:

1. The type of meaning it expresses
2. The type of affixes it takes
3. The structure in which it occurs

In terms of phrase structure rules

Phrase structure rules

Phrase-structure rules are a way to describe a given language's syntax. They are used to break down a natural language sentence into its constituent parts namely phrasal categories and lexical categories...

, phrasal categories can occur to the left side of the arrow while lexical categories cannot.

The lexical categories are traditionally called the parts of speech. They include nouns, verbs, adjective

Adjective

In grammar, an adjective is a 'describing' word; the main syntactic role of which is to qualify a noun or noun phrase, giving more information about the object signified....

s, and so on.

See also

• Syntax
  Syntax
  In linguistics, syntax is the study of the principles and rules for constructing phrases and sentences in natural languages....
  
  
• Phrase
  Phrase
  In everyday speech, a phrase may refer to any group of words. In linguistics, a phrase is a group of words which form a constituent and so function as a single unit in the syntax of a sentence. A phrase is lower on the grammatical hierarchy than a clause....
  
  
• Clause
  Clause
  In grammar, a clause is the smallest grammatical unit that can express a complete proposition. In some languages it may be a pair or group of words that consists of a subject and a predicate, although in other languages in certain clauses the subject may not appear explicitly as a noun phrase,...
  
  
• Sentence (linguistics)
  Sentence (linguistics)
  In the field of linguistics, a sentence is an expression in natural language, and often defined to indicate a grammatical unit consisting of one or more words that generally bear minimal syntactic relation to the words that precede or follow it...
  
  
• Lexical category
  Lexical category
  In grammar, a part of speech is a linguistic category of words , which is generally defined by the syntactic or morphological behaviour of the lexical item in question. Common linguistic categories include noun and verb, among others...
  
  
• Phrase structure rules
  Phrase structure rules
  Phrase-structure rules are a way to describe a given language's syntax. They are used to break down a natural language sentence into its constituent parts namely phrasal categories and lexical categories...