corundum

n [U] hard crystallized mineral used chiefly in abrasives, or in powder form for polishing 刚玉; 刚石; 金刚砂.

corrugate, corrugated, corrugated iron, corrugation, corrupt, corrupted, corruptibility, corruptible, corruption, corruptly, corruptness, corsage, corsair, corselet (also corslet), corset, cortege (also cortege), cortex, cortical, cortisol, cortisone, coruscate, coruscation, corvette, cos, cos (also cos), cosec, cosecant, coset, cosh, cosily, cosine, cosiness, cosmetic, cosmetic surgery, cosmetically, cosmetician, cosmetics, cosmic, cosmic being, cosmic dust,