Function word in the context of "Interrogative pronoun"

In grammar, a part of speech or part-of-speech (abbreviated as POS or PoS, also known as word class or grammatical category) is a category of words (or, more generally, of lexical items) that have similar grammatical properties. Words that are assigned to the same part of speech generally display similar syntactic behavior (they play similar roles within the grammatical structure of sentences), sometimes similar morphological behavior in that they undergo inflection for similar properties and even similar semantic behavior. Commonly listed English parts of speech are noun, verb, adjective, adverb, pronoun, preposition, conjunction, interjection, numeral, article, and determiner.

Other terms than part of speech—particularly in modern linguistic classifications, which often make more precise distinctions than the traditional scheme does—include word class, lexical class, and lexical category. Some authors restrict the term lexical category to refer only to a particular type of syntactic category; for them the term excludes those parts of speech that are considered to be function words, such as pronouns. The term form class is also used, although this has various conflicting definitions. Word classes may be classified as open or closed: open classes (typically including nouns, verbs and adjectives) acquire new members constantly, while closed classes (such as pronouns and conjunctions) acquire new members infrequently, if at all.

In grammar, the term particle (abbreviated PTCL) has a traditional meaning, as a part of speech that cannot be inflected, and a modern meaning, as a function word (functor) associated with another word or phrase in order to impart meaning. Although a particle may have an intrinsic meaning and may fit into other grammatical categories, the fundamental idea of the particle is to add context to the sentence, expressing a mood or indicating a specific action.

In English, for example, the phrase "oh well" has no purpose in speech other than to convey a mood. The word "up" would be a particle in the phrase "look up" (as in "look up this topic"), implying that one researches something rather than that one literally gazes skywards.

A syntactic category is a syntactic unit that theories of syntax assume. Word classes, largely corresponding to traditional parts of speech (e.g. noun, verb, preposition, etc.), are syntactic categories. In phrase structure grammars, the phrasal categories (e.g. noun phrase, verb phrase, prepositional phrase, etc.) are also syntactic categories. Dependency grammars, however, do not acknowledge phrasal categories (at least not in the traditional sense).

Word classes considered as syntactic categories may be called lexical categories, as distinct from phrasal categories. The terminology is somewhat inconsistent between the theoretical models of different linguists. However, many grammars also draw a distinction between lexical categories (which tend to consist of content words, or phrases headed by them) and functional categories (which tend to consist of function words or abstract functional elements, or phrases headed by them). The term lexical category therefore has two distinct meanings. Moreover, syntactic categories should not be confused with grammatical categories (also known as grammatical features), which are properties such as tense, gender, etc.

In morphology and syntax, a clitic (/ˈklɪtɪk/ KLIT-ik, backformed from Greek ἐγκλιτικός enklitikós "leaning" or "enclitic") is a morpheme that has syntactic characteristics of a word, but depends phonologically on another word or phrase. In this sense, it is syntactically independent but phonologically dependent—always attached to a host. A clitic is pronounced like an affix, but plays a syntactic role at the phrase level. In other words, clitics have the form of affixes, but the distribution of function words.

Clitics can belong to any grammatical category, although they are commonly pronouns, determiners, or adpositions. Note that orthography is not always a good guide for distinguishing clitics from affixes: clitics may be written as separate words, but sometimes they are joined to the word they depend on (like the Latin clitic -que, meaning "and") or separated by special characters such as hyphens or apostrophes (like the English clitic 's in "it's" for "it has" or "it is").

In linguistics, a pro-form is a type of function word or expression that stands in for (expresses the same content as) another word, phrase, clause or sentence where the meaning is recoverable from the context. They are used either to avoid repetitive expressions or in quantification (limiting the variables of a proposition).

Pro-forms are divided into several categories, according to which part of speech they substitute: