The Collaborative International Dictionary of English v.0.48:

Headman \Head"man`\ (h[e^]d"m[a^]n`), n.; pl. Headmen
   (-m[e^]n`). [AS. he['a]fodman.]
   A head or leading man, especially of a village community.
   Headmold shot

WordNet (r) 3.0 (2006):

headman
    n 1: an executioner who beheads the condemned person [syn:
         headsman, headman]
    2: the head of a tribe or clan [syn: headman, tribal chief,
       chieftain, chief]

Moby Thesaurus II by Grady Ward, 1.0:

71 Moby Thesaurus words for "headman":
   Big Brother, alderman, archon, auditor, bailie, boatswain, boss,
   burghermaster, burgomaster, cabinet member, cabinet minister,
   chancellor, chief, chieftain, city councilman, city father,
   city manager, cock, commissar, commissioner, comptroller,
   controller, councillor, councilman, councilwoman,
   county commissioner, county supervisor, elder, floor manager,
   floorman, floorwalker, foreman, gaffer, ganger, head, hierarch,
   honcho, induna, inspector, leader, legislator, lord mayor,
   magistrate, maire, master, mayor, minister, minister of state,
   monitor, noncommissioned officer, overman, overseer, portreeve,
   proctor, reeve, secretary, secretary of state, selectman, sirdar,
   slave driver, straw boss, subforeman, super, superintendent,
   supervisor, surveyor, syndic, taskmaster, undersecretary, visitor,
   warden