Lewis & Short

marcor, ōris, m. [marceo], a withering: segetum, Sen. Q. N. 3, 27, 4.
Hence, Transf.

  1. I. Decay, rottenness (not anteAug.): panni marcor, a rotten rag, Plin. 22, 22, 46, § 94.
  2. II. Faintness, languor, indolence: marcor, et inexpugnabilis dormiendi necessitas, Cels. 3, 20: cernitis expositas turpi marcore cohortes, i. e. somno, Stat. Th. 10, 269: maeror marcorque, melancholy, Sen. Tranq. 2, 8: ducis, indolence, worthlessness, Vell. 2, 119, 2.