signpost (n.)youdaoicibaDictYouDict[signpost 词源字典]
also sign-post, 1610s, "sign on a post, usually indicating an inn or shop," from sign (n.) + post (n.1). Meaning "guide- or direction-post along a road" is attested from 1863. Figurative sense is from 1889.[signpost etymology, signpost origin, 英语词源]