In publishing, the pile of unsolicited manuscripts received by the publisher. For most magazines and book publishers, the slush pile is a last resort when you must publish something but don't have anything else.

I worked for a few weeks as an assistant dramaturg in a large theater in Texas, and we also had a slush pile (in our case, of unsolicited scripts for plays). I can attest to the fact that the quality of manuscripts in the slush pile tends to be fairly low. But once in a while you find a diamond in the rough.