The term refers to work on syntax (or phonology) that does not extend into semantics. So, basically anything Chomsky writes is on narrow syntax, whereas anythin

The term refers to work on syntax (or phonology) that does not extend into semantics. So, basically anything Chomsky writes is on narrow syntax, whereas anything (say) Irene Heim or Barbara Partee writes is concerned with a broader notion of syntax (which includes semantics).