noun A comb or tuft of feathers, fur, or skin on the head of a bird or other animal. (a large game bird with a conspicuous erect red crest) The top of a mountain or hill. (she reached the crest of the hill) The curling foamy top of a wave. (a high wave formed by the meeting of two crests) A distinctive device representing a family or corporate body, borne above the shield of a coat of arms (originally as worn on a helmet) or separately reproduced, for example on writing paper.
verb Reach the top of (a hill or wave) (she crested a hill and saw the valley spread out before her) (of a wave) form a curling foamy top. (the swell begins to curl and crest) Have attached at the top. (his helmet was crested with a fan of spikes)