The Collaborative International Dictionary of English v.0.48:

mayor \may"or\, n. [OE. maire, F. maire, fr. L. major greater,
   higher, nobler, compar. of magnus great; cf. Sp. mayor. See
   Major, and cf. Merino.]
   The chief magistrate of a city or borough; the chief
   administrative officer of a municipal corporation. In some
   American cities there is a city court of which the major is
   chief judge. The post is usually elective, its holder chosen
   by the electorate of the entire city.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "mayor":
   alderman, archon, bailie, burghermaster, burgomaster,
   cabinet member, cabinet minister, chancellor, city councilman,
   city father, city manager, commissar, commissioner, councillor,
   councilman, councilwoman, county commissioner, county supervisor,
   elder, headman, induna, legislator, lord mayor, magistrate, maire,
   minister, minister of state, portreeve, reeve, secretary,
   secretary of state, selectman, supervisor, syndic, undersecretary,
   warden