The Collaborative International Dictionary of English v.0.48:

Legumin \Le*gu"min\ (-m[i^]n), n. [Cf. F. l['e]gumine.]
   (Physiol. Chem.)
   An albuminous substance resembling casein, found as a
   characteristic ingredient of the seeds of leguminous and
   grain-bearing plants.
   [1913 Webster]