The Collaborative International Dictionary of English v.0.48:

Lamp-post \Lamp"-post`\, n.
   A post (generally a pillar of iron) supporting a lamp or
   lantern for lighting a street, park, etc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lamppost
    n 1: a metal post supporting an outdoor lamp (such as a
         streetlight)