The Collaborative International Dictionary of English v.0.48:

Councilman \Coun"cil*man\ (koun"s[i^]l*man), n.; pl.
   Councilmen (koun"s[i^]l*men).
   A member of a council, especially of the common council of a
   city; a councilor.
   [1913 Webster]

WordNet (r) 3.0 (2006):

councilman
    n 1: a man who is a council member

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "councilman":
   MP, Member of Congress, Member of Parliament, alderman, archon,
   assemblyman, bailie, burghermaster, burgomaster, cabinet member,
   cabinet minister, chancellor, chosen freeholder, city councilman,
   city father, city manager, commissar, commissioner, congressman,
   congresswoman, councillor, councilwoman, county commissioner,
   county supervisor, elder, floor leader, headman, induna, lawgiver,
   lawmaker, legislator, lord mayor, magistrate, maire,
   majority leader, mayor, minister, minister of state,
   minority leader, party whip, portreeve, reeve, representative,
   secretary, secretary of state, selectman, senator, solon,
   state senator, supervisor, syndic, undersecretary, warden, whip