A semantic link is a typed link where the type carries some semantics. That is, it does not simply describe a characteristic of the link, but describes some external relationship or issue.

An example of a semantic link would be (any syntax expressing) "A is-mother-of B". Some other relations like "B is-child-of A" may be implied by it.

Such links are the basis of a semantic network. The Semantic Web is only one example of these.