The Collaborative International Dictionary of English v.0.48:

Coagulum \Co*ag"u*lum\, n.; pl. Coagula. [L. See Coagulate,
   a.]
   The thick, curdy precipitate formed by the coagulation of
   albuminous matter; any mass of coagulated matter, as a clot
   of blood.
   [1913 Webster]