a black or brown-speckled seabird of the genus Cepphus, of northern seas, having a sharply pointed black bill, red legs, and white wing patches, as C. grylle(black guillemot) of the North Atlantic and the similar C. columba(pigeon guillemot) of the North Pacific.
British. a murre of the genus Uria.
Origin of guillemot
1670-80; < French, apparently diminutive of Guillaume William