Entry 2 senses · 2 variants Webster, 1913 mains /(mānz)/ · IPA /meɪnz/ n. n. 01 n. The farm attached to a mansion house; a manse. 1. The farm attached to a mansion house; a manse.[Scot. or Brit. dial.] 02 n. The source of electrical power in a building; the wiring system of a building. 1. The source of electrical power in a building; the wiring system of a building.(Electricity)