The Collaborative International Dictionary of English v.0.48:

doorman \doorman\ n.
   someone who guards the entrance to a building.

   Syn: doorkeeper, door guard, hall porter, porter, gatekeeper.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

doorman
    n 1: someone who guards an entrance [syn: doorkeeper,
         doorman, door guard, hall porter, porter,
         gatekeeper, ostiary]