gluten (n.)

1630s, "a sticky substance," from Middle French gluten "sticky substance" (16c.) or directly from Latin gluten (glutin-) "glue" (see glue (n.)). Used 16c.-19c. for the part of animal tissue now called fibrin; used since 1803 of the nitrogenous part of the flour of wheat or other grain; hence glutamic acid (1871), a common amino acid, and its salt, glutamate.