The Collaborative International Dictionary of English v.0.48:

Rocaille \Ro`caille"\, n. [F. Cf. Rock a stone.] (Art)
   (a) Artificial rockwork made of rough stones and cement, as
       for gardens.
   (b) The rococo system of scroll ornament, based in part on
       the forms of shells and water-worn rocks.
       [Webster 1913 Suppl.]