1.The general and popular term for a firm, upright, insulated support for a superstructure; a pier, column, or post; also, a column or shaft not supporting a superstructure, as one erected for a monument or an ornament. "Jacob set a pillar upon her grave." "The place... vast and proud, Supported by a hundred pillars stood."
2.Figuratively, that which resembles such a pillar in appearance, character, or office; a supporter or mainstay; as, the Pillars of Hercules; a pillar of the state. "You are a well-deserving pillar." "By day a cloud, by night a pillar of fire."
3.(R. C. Ch.) A portable ornamental column, formerly carried before a cardinal, as emblematic of his support to the church. (Obs.)
4.(Man.) The center of the volta, ring, or manege ground, around which a horse turns.