The Collaborative International Dictionary of English v.0.48:
Winesap \Wine"sap`\, n. [Wine + sap for sop.] A variety of winter apple of medium size, deep red color, and yellowish flesh of a rich, rather subacid flavor. [Webster 1913 Suppl.]WordNet (r) 3.0 (2006):
Winesap n 1: crisp apple with dark red skin