I. The hardened, thick skin upon animal bodies: “fere res omnes aut corio sunt Aut etiam conchis aut callo aut cortice tectae,” Lucr. 4, 935: “calceamentum solorum callum,” Cic. Tusc. 5, 32, 90: “pedum,” Plin. 22, 25, 60, § 127; cf. id. 9, 35, 54, § 108.—Plur., Suet. Aug. 80.—Hence,
B. Meton.
1. The hard flesh of certain animals: “aprugnum,” Plaut. Poen. 3, 2, 2; id. Pers. 2, 5, 4; for which absol. callum, id. Capt. 4, 3, 4; id. Ps. 1, 2, 33: “manus elephanti,” Plin. 8, 10, 10, § 31: “locustarum,” id. 9, 30, 50, § 95.—
2. The hard skin or the hard flesh of plants: “uvarum,” Plin. 14, 1, 3, § 14: “pirorum ac malorum,” id. 15, 28, 34, § 116: “fungorum,” id. 22, 23, 47, § 96: “foliorum,” id. 16, 22, 34, § 82; Pall. Mart. 10, 28 al.—
3. The hard covering of the soil: “terrae,” Plin. 17, 5, 3, § 33; 19, 2, 11, § 33; 31, 4, 30, § 53; also, of the hardness of salt: “salis,” id. 16, 12, 23, § 56.—
II. Trop., hardness, callousness, insensibility, stupidity (rare; “most freq. in Cic.): ipse labor quasi callum quoddam obducit dolori,” renders callous to pain, Cic. Tusc. 2, 15, 36; 3, 22, 53; id. Fam. 9, 2, 3: “ducere,” Sen. Cons. ad Marc. 8, 2: “inducere,” Quint. 12, 6, 6.