The Collaborative International Dictionary of English v.0.48:

Marinade \Mar`i*nade"\, n. [F.: cf. It. marinato marinade, F.
   mariner to preserve food for use at sea. See Marinate.]
   (Cookery)
   A brine or pickle containing wine or vinegar, with opil,
   herbs, and spices, for enriching the flavor of meat and fish,
   which are steeped in it prior to cooking.
   [1913 Webster]

WordNet (r) 3.0 (2006):

marinade
    n 1: mixtures of vinegar or wine and oil with various spices and
         seasonings; used for soaking foods before cooking
    v 1: soak in marinade; "marinade herring" [syn: marinade,
         marinate]