subordinating conjunction

  edgood  —  Grammar Tips
We have a long list of subordinating conjunctions. These words are used to start a subordinate clause, which can act as an adjective, adverb, or noun. Examples include after, although, as, as far as, as if, as long as, as though, because, before, how, if, in order that, provided that, since, so (that), that, though, till, unless, until, what, whatever, when, whenever, where, wherever, while, and others.

You can use subordinating conjunctions to form what's called an elliptical clause, also called a truncated clause.

For a discussion, see elliptical clause.