can·ker·ous \ˈkaŋk(ə)rəs, -ˈai-\adjective 1. a.obsolete: having the effect of a spreading sore b.: eating into and corrupting the flesh 2.: that spreads corruption of mind or spirit < his firmness of mind soon relapsed into a cankerous intolerance — Maurice Cranston > 3.: affected with or caused by canker < a cankerous stem disease >