An ELT Glossary : Proform

 

A proform is any word which can replace another word, phrase or clause in a sentence or utterance when the meaning is recoverable from the linguistic or extra-linguistic context. Proforms thus avoid unnecessary repetion or redundancy.

The most common types are pronouns, which replace nouns or noun phrases.

John isn't here today. He's ill    (He replaces John.)

I need a new t-shirt. I'll buy one when I go to the market on Friday.    (One replaces a new T-shirt).

That's the man who told me    (Who replaces the man.) 

However, other words can also be proforms. For example, does acting as operator can replace a full verb phrase :

I don't like dogs, but Jane does     (Does replaces the verb phrase likes dogs)

I was at the market this morning and I bought a t-shirt there. (The adverb there replaces the prepositional phrase at the market)

I'm not sure if John will be at the meeting, but I think so.  (The adverb so replaces the clause that John will be at the meeting).

Proforms are thus devices of reference and substitution.