The Collaborative International Dictionary of English v.0.48:

Crup \Crup\ (kr?p), a. [Cf. OHG. grop, G. grob, coarse.]
   Short; brittle; as, crup cake. --Todd.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Crup \Crup\ (kr?p), n.
   See Croup, the rump of a horse.
   [1913 Webster]