(syn. Larus Ϯ Black-headed Gull L. ridibundus) Gr. χρωικος khrōikos coloured < χρωζω khrōzō to colour, to stain; -κεφαλος -kephalos -headed < κεφαλη kephalē head; "Chroicocephalus for a new subgenus under Larus, Linn., for the reception of such gulls as have the tarsi slender, thighs considerably denuded, hind toe very small, head only, or head and upper part of neck, dark-coloured in the summer state of plumage ...derived from two Greek words, κροικος, coloured, and κεφαλη, head; signifying that the birds classed under that name have coloured heads" (Eyton per Wharton 1878). Var. Chroecocephalus, Chroeocephalus, Chroiococephalus, Chroiocephalus, Chraeococephalus, Chraecocephalus, Chroocephalus, Croicocephalus, Kroikocephalus, Kroicocephalus, Krokocephalus.