The Collaborative International Dictionary of English v.0.48:

Gluten \Glu"ten\, n. [L., glue: cf. F. gluten. See Glue.]
   (Chem.)
   The viscid, tenacious substance which gives adhesiveness to
   dough.
   [1913 Webster]

   Note: Gluten is a complex and variable mixture of glutin or
         gliadin, vegetable fibrin, vegetable casein, oily
         material, etc., and is a very nutritious element of
         food. It may be separated from the flour of grain by
         subjecting this to a current of water, the starch and
         other soluble matters being thus washed out.
         [1913 Webster]

   Gluten bread, bread containing a large proportion of
      gluten; -- used in cases of diabetes.

   Gluten casein (Chem.), a vegetable proteid found in the
      seeds of grasses, and extracted as a dark, amorphous,
      earthy mass.

   Gluten fibrin (Chem.), a vegetable proteid found in the
      cereal grains, and extracted as an amorphous, brownish
      yellow substance.
      [1913 Webster]

WordNet (r) 3.0 (2006):

gluten
    n 1: a protein substance that remains when starch is removed
         from cereal grains; gives cohesiveness to dough

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "gluten":
   albumen, batter, bonnyclabber, butter, clabber, cornstarch, cream,
   curd, dough, egg white, gaum, gel, gelatin, glair, glop, glue, goo,
   gook, goop, gruel, gumbo, gunk, jam, jell, jelly, loblolly,
   molasses, mucilage, mucus, pap, paste, porridge, pudding, pulp,
   puree, putty, rob, semifluid, semiliquid, size, soup, starch,
   sticky mess, syrup, treacle