Source : Webster's Revised Unabridged Dictionary (1913)

Cammock \Cam"mock\, n. [AS. cammoc.] (Bot.)
   A plant having long hard, crooked roots, the {Ononis
   spinosa}; -- called also {rest-harrow}. The {Scandix
   Pecten-Veneris} is also called cammock.

Source : WordNet®

Ononis spinosa
     n : Eurasian plant having loose racemes of pink or purple
         flowers and spiny stems and tough roots [syn: {restharrow},
          {rest-harrow}]