The Collaborative International Dictionary of English v.0.48:

Mucous \Mu"cous\, a. [L. mucosus, fr. mucus mucus.]
   1. Of, pertaining to, or resembling, mucus; slimy, ropy, or
      stringy, and lubricous; as, a mucous substance.
      [1913 Webster]

   2. Secreting a slimy or mucigenous substance; as, the mucous
      membrane.
      [1913 Webster]

   Mucous membrane. (Anat.) See under Membrane.

   Mucous patches (Med.), elevated patches found in the mucous
      membranes of the mouth and anus, usually due to syphilis.


   Mucous tissue (Anat.), a form of connective tissue in an
      early stage of development, found in the umbilical cord
      and in the embryo, and also in certain tumors called
      myxomata.
      [1913 Webster]

WordNet (r) 3.0 (2006):

mucous
    adj 1: of or secreting or covered with or resembling mucus;
           "mucous tissue"; "mucous glands of the intestine" [syn:
           mucous, mucose]