Noun | 1. | ![]() auk - black-and-white short-necked web-footed diving bird of northern seas Cepphus, genus Cepphus - a genus of birds including: guillemots black guillemot, Cepphus grylle - northern Atlantic guillemot Cepphus columba, pigeon guillemot - northern Pacific guillemot murre - black-and-white diving bird of northern seas |