The Collaborative International Dictionary of English v.0.48:

Parotitis \Par`o*ti"tis\, n. [NL. See Parotid, and -itis.]
   (Med.)
   Inflammation of the parotid glands.
   [1913 Webster]

   Epidemic parotitis or Infectious parotitis, mumps.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mumps \Mumps\, n. [Prov. E. mump to be sulky. Cf. Mump,
   Mumble, and Mum.]
   1. pl. Sullenness; silent displeasure; the sulks. --Skinner.
      [1913 Webster]

   2. [Prob. so called from the patient's appearance.] (Med.) A
      specific infectious febrile disorder characterized by a
      nonsuppurative inflammation of the parotid glands, and
      sometimes causing inflammation of the testes or ovaries;
      also called epidemic parotitis or infectious
      parotitis. It is caused by infection with a
      paramyxovirus.
      [1913 Webster +PJC]