What is "pro-sentence"

n. (context grammar English) a function word or expression that substitutes for a whole sentence whose content is recoverable from the context

A pro-sentence is a function word or expression that substitutes for a whole sentence whose content is recoverable from the context. A pro-sentence is a kind of pro-form and is therefore anaphoric.

In English, yes, no, okay and amen are common pro-sentences. In response to the question "Does Mars have two moons?", the sentence "Yes" can be understood to abbreviate "Mars has two moons."

Pro-sentences are sometimes seen as grammatical interjections, since they are capable of very limited syntactical relations. But they can also be classified as a distinct part of speech, given that (other) interjections have meanings of their own and are often described as expressions of feelings or emotions.