Lewis & Short

cōdĭcilli, ōrum (sing. post-class. and rare in the meaning II. B. 2. infra, Cod. Just. 1, 5, 4, § 5; Cod. Th. 8, 18, 7; 16, 5, 40; Dig. 29, 7, 19; cf. ib. 50, 16, 148), m. dim. [codex = caudex].

  1. I. Wood cut and split for burning, only in Cato, R. R. 37, 5; 130.
  2. II. (Acc. to caudex, III., a writing-tablet; hence) A writing, letter, esp. a short writing, note, billet, a petition, etc.; cf. Plin. 13, 13, 27, § 89, and 33, 1, 4, § 12.
    1. A. In gen., Cic. Phil. 8, 10, 28; id. Fam. 6, 18, 1; 9, 26, 1; id. Q. Fr. 2, 9 (11), 1; id. Att. 4, 8, 2: cum codicillis venit puer, Sulp. ap. Cic. Fam. 4, 12, 2; Suet. Tib. 51; id. Claud. 5; id. Oth. 10; id. Gram. 14; Sen. Ep. 55, 10; Tac. A. 4, 39; 6, 9; Suet. Ner. 49; Sen. Clem. 15 al.
    2. B. Specif., in the time of the empire,
      1. 1. A writing of the emperor conferring some privilege, a diploma, a cabinet order, Suet. Tib. 22, 42; id. Calig. 18; 54; id. Claud. 29; Cod. Th. 6, 4, 23.
      2. 2. A brief testamentary order, usu. as an addition or appendix to a will, a codicil, Plin. Ep. 2, 16, 1; Tac. A. 15, 64 fin.; cf. Dig. 29, tit. 7: de jure codicillorum.