Lewis & Short

caldārĭus (călĭd-), a, um, adj. [caldus = calidus],

  1. I. pertaining to or suitable for warming. cella, a warm bath, Plin. Ep. 5, 6, 26.
    1. B. Subst.
      1. 1. caldārĭa, ae, f.
        1. a. A warm bath, Marc. Emp. 25.
        2. b. A pot for boiling, Vulg. 1 Reg. 2, 14; App. Herb. 59.
      2. 2. caldārĭum, ii, n.
        1. a. A hot bath, Vitr. 5, 10, 1; 8, 2, 4; Sen. Ep. 86, 11; Cels. 1, 4.
        2. b. A room containing warm water for bathing, Vitr. 5, 10, 1.
  2. II. Esp.: calidaria maltha, for plastering the walls in baths, Pall. 1, 41, 1: caldarium aes, that is prepared by heat or fusion, Plin. 34, 8, 20, § 94.