The Collaborative International Dictionary of English v.0.48:

Corbiestep \Cor"bie*step`\, n. (Arch.)
   One of the steps in which a gable wall is often finished in
   place of a continuous slope; -- also called crowstep.
   [1913 Webster]

WordNet (r) 3.0 (2006):

corbiestep
    n 1: (architecture) a step on the top of a gable wall [syn:
         corbel step, corbie-step, corbiestep, crow step]