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]