The Collaborative International Dictionary of English v.0.48:
Signpost \Sign"post`\, n. A post on which a sign hangs, or on which papers are placed to give public notice of anything. [1913 Webster] SikWordNet (r) 3.0 (2006):
signpost n 1: a post bearing a sign that gives directions or shows the way [syn: signpost, guidepost] v 1: mark with a signpost, as of a path