1a 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
a plume of feathers on a helmet.
2the top of a mountain or hill:she reached the crest of the hill
Anatomy a ridge along the surface of a bone:biopsy specimens of the iliac crest were obtained under local anaesthesia
the upper line of the neck of a horse or other mammal:take hold of the mane halfway up the horse’s crest
3the curling foamy top of a wave:a high wave formed by the meeting of two crests
4 Heraldry 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.
1 [with object] reach the top of (a hill or wave):she crested a hill and saw the valley spread out before her
[no object]US (of a river, flood, etc.) rise to its highest level.
2 [no object] (of a wave) form a curling foamy top:the swell begins to curl and crest
3 (be crested with) have attached at the top:his helmet was crested with a fan of spikes
on the crest of a wave
at a very successful point:his career is on the crest of a wave at present