See under guillemot(def 1).
Origin of black guillemot
First recorded in 1760–70
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
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
a common guillemot, Cepphus grylle : its summer plumage is black with white wing patches and its winter plumage white with greyish wings
any northern oceanic diving bird of the genera Uria and Cepphus, having a black-and-white plumage and long narrow bill: family Alcidae (auks, etc), order Charadriiformes
Word Origin for guillemot
C17: from French, diminutive of Guillaume William
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012