Complementizer

In linguistics (especially generative grammar), complementizer or complementiser (glossing abbreviattion: comp) is a lexical category (part of speech) that includes those words that can be used to turn a clause into the subject or object of a sentence. For example, the word that may be called a complementizer in English sentences like Mary believes that it is raining. The concept of complementizers is specific to certain modern grammatical theories; in traditional grammar, such words are normally considered either conjunctions or relative pronouns.

The standard abbreviation for complementizer is C. The complementizer is often held to be the syntactic head of a full clause, which is therefore often represented by the abbreviation CP (for complementizer phrase). Evidence that the complementizer functions as the head of its clause includes the fact that it is commonly the last element in a clause in head-final languages like Korean or Japanese, in which other heads follow their complements, whereas it appears at the start of a clause in head-initial languages such as English, where heads normally precede their complements.

It is common for the complementizers of a language to develop historically from other syntactic categories (a process known as grammaticalization). Across the languages of the world, it is especially common for pronouns or determiners to be used as complementizers (e.g., English that). Another frequent source of complementizers is the class of interrogative words. It is especially common for a form that otherwise means what to be borrowed as a complementizer, but other interrogative words are often used as well; e.g., colloquial English I read in the paper how it's going to be cold today, with unstressed how roughly equivalent to that). English for in sentences like I would prefer for there to be a table in the corner shows a preposition that has arguably developed into a complementizer. (The sequence for there in this sentence is not a prepositional phrase under this analysis.) In many languages of West Africa and South Asia, the form of the complementizer can be related to the verb say. In these languages, the complementizer is also called the quotative. The quotative performs many extended functions in these languages.

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