What is a contextual sentence?

What is a contextual sentence?

A contextual sentence has meaning that can be derived from the words alone and their arrangement in a sentence having regard to the rules of language alone and disregarding extra-textual factors like purpose or consequences.

Therefore, the sentence alone and the words arranged within it give you its meaning, you don't need to know the sentences before or after it, why it was written, or any other extraneous information.

Hope that helps!