mains \mains\ (m[=a]nz), n. [Scot. See {Manse}.] The farm attached to a mansion house; a manse. [Scot. or Brit. dial.] [1913 Webster]
mains \mains\ (m[=a]nz), n. (Electricity) The source of electrical power in a building; the wiring system of a building. [PJC]