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]

WordNet (r) 3.0 (2006):

coagulum
    n 1: a lump of material formed from the content of a liquid
         [syn: clot, coagulum]