Lewis & Short

commŏnĭtōrĭus, a, um, adj. [commonitor],

  1. I. suitable for reminding (late Lat.), Cod. Just. 1, 3, 33.
  2. II. Subst.: commŏ-nĭtōrĭum, ii, n., a writing for reminding, a letter of instructions, Amm. 28, 1, 1; Symm. Ep. 5, 21; Cod. Th. 2, 29, 2, § 3; 6, 29, 10; Aug. Ep. 129 fin.
    1. B. Trop., a means of reminding, Sid. Ep. 8, 11.