Pro-form

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.^[1] 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:

A pronoun substitutes a noun or a noun phrase, with or without a determiner: it, this.
A prop-word: one, as in "the blue one"
A pro-adjective substitutes an adjective or a phrase that functions as an adjective: so as in "It is less so than we had expected."
A pro-adverb substitutes an adverb or a phrase that functions as an adverb: how or this way.
A pro-verb substitutes a verb or a verb phrase: do, as in: "I will go to the party if you do".
A pro-sentence substitutes an entire sentence or subsentence: Yes, or that as in "That is true".^[2]

An interrogative pro-form is a pro-form that denotes the (unknown) item in question and may itself fall into any of the above categories.

The rules governing allowable syntactic relations between certain pro-forms (notably personal and reflexive/reciprocal pronouns) and their antecedents have been studied in what is called binding theory.

^ Crystal, David (1985). A dictionary of linguistics and phonetics (2nd ed.). Basil Blackwell.
^ Rödl, Sebastian (2012). Categories of the Temporal. Cambridge, Massachusetts: Harvard University Press. pp. 22–25. ISBN 978-0-674-04775-4.

[1] Crystal, David (1985). A dictionary of linguistics and phonetics (2nd ed.). Basil Blackwell.

[2] Rödl, Sebastian (2012). Categories of the Temporal. Cambridge, Massachusetts: Harvard University Press. pp. 22–25. ISBN 978-0-674-04775-4.

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