The Collaborative International Dictionary of English v.0.48:
collard \collard\ n. 1. a variety of kale (Brassica oleracea) having smooth leaves; a type of colewort. It is grown in the southern U. S. [WordNet 1.5 +PJC]WordNet (r) 3.0 (2006):
collard n 1: variety of kale having smooth leaves