The Collaborative International Dictionary of English v.0.48:

Ondoyant \On`do`yant"\, a. [F., p.pr. of ondoyer to undulate,
   fr. onde wave, L. unda.] (Art)
   Wavy; having the surface marked by waves or slightly
   depressed furrows; as, ondoyant glass.
   [Webster 1913 Suppl.]