Lewis & Short

ātrāmentum, i, n. [ater], any black liquid: sepiae, Cic. N D. 2, 50, 127.

  1. I. Writing-ink, ink; in Vitr. 7, 10, and Plin. 27, 7, 28, § 52, called atramentum librarium: calamo et atramento temperato, Cic. ad Q. Fr. 2, 15, 6: per atramentum et calamum scribere, Vulg. 3 Joan. 13; Petr. 102, 13; Hor. Ep. 2, 1, 236; Vulg. Jer. 36, 18; ib. 2 Joan. 12.
  2. II. A black pigment or color, Vitr. 7, 10; 7, 4; Plin. 35, 6, 25, § 41; also a fine, dark varnish, lacquer, id. 35, 10, 36, § 97: Indicum, India or China ink, id. 35, 6, 25, § 43.
  3. III. A blacking for coloring leather: atramentum sutorium, Plin. 34, 12, 32, § 123; Cic. Fam. 9, 21 fin.
  4. IV. In comic language: Sc. Unā operā ebur atramento candefacere postulas. Phil. Lepide dictum de atramento atque ebore, i. e. you require something impossible, Plaut. Most. 1, 3, 102.