The Collaborative International Dictionary of English v.0.48:

Doorkeeper \Door"keep`er\, n.
   One who guards the entrance of a house or apartment; a
   porter; a janitor.
   [1913 Webster]

WordNet (r) 3.0 (2006):

doorkeeper
    n 1: an official stationed at the entrance of a courtroom or
         legislative chamber [syn: usher, doorkeeper]
    2: the lowest of the minor Holy Orders in the unreformed Western
       Church but now suppressed by the Roman Catholic Church [syn:
       doorkeeper, ostiary, ostiarius]
    3: someone who guards an entrance [syn: doorkeeper, doorman,
       door guard, hall porter, porter, gatekeeper,
       ostiary]

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "doorkeeper":
   acolyte, acolytus, cerberus, concierge, deacon, diaconus, doorman,
   exorcist, exorcista, gatekeeper, holy orders, janitor, lector,
   major orders, minor orders, ostiarius, ostiary, porter, presbyter,
   priest, reader, receptionist, subdeacon, subdiaconus, usher,
   warden



Easton's 1897 Bible Dictionary:

Door-keeper
   This word is used in Ps. 84:10 (R.V. marg., "stand at the
   threshold of," etc.), but there it signifies properly "sitting
   at the threshold in the house of God." The psalmist means that
   he would rather stand at the door of God's house and merely look
   in, than dwell in houses where iniquity prevailed.

     Persons were appointed to keep the street door leading into
   the interior of the house (John 18:16, 17; Acts 12:13).
   Sometimes females held this post.