The Collaborative International Dictionary of English v.0.48:

Greaves \Greaves\ (gr[=e]vz), n. pl. [Cf. dial. Sw. grevar
   greaves, LG. greven, G. griebe, also AS. greofa pot. Cf.
   Gravy.]
   The sediment of melted tallow. It is made into cakes for
   dogs' food. In Scotland it is called cracklings. [Written
   also graves.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

cracklings
    n 1: the crisp residue left after lard has been rendered