Lewis & Short

Maenĭus, a, the name of a Roman gens: C. Maenius, consul A. U. C. 416, Liv. 8, 13, 1.
Hence,

  1. A. Maenĭus, a, um, adj., of or belonging to a Mænius, Mænian: Maenia lex, proposed by the people’s tribune Mænius, A. U. C. 468, Cic. Brut. 14, 55.
    Esp. freq., Maenĭa Cŏlumna, ae, f., a pillar in the Forum, at which thieves and refractory slaves were scourged, and to which bad debtors were summoned, a whipping-post, Cic. Div. in Caecil. 16, 50; id. Sest. 58, 124.
  2. B. Maenĭānum, i, n., a projecting gallery, balcony of a house (first made use of by a Mænius); commonly used in the plur.: Maeniana appellata sunt a Maenio censore, qui primus in Foro ultra columnas tigna projecit, quo ampliarentur superiora spectacula, Paul. ex Fest. p. 134 Müll.; Cic. Ac. 2, 22, 70; Suet. Calig. 18; Vitr. 5, 1, 2; Varro ap. Plin. 35, 10, 37, § 113; Dig. 50, 16, 242; Cod. Just. 8, 10, 11.
    In sing.: Maenianum conscendere, Val. Max. 9, 12, 7.