A group of islands in the English Channel off the NW coast of France, of which the largest are Jersey, Guernsey, and Alderney; population 164,000 (estimated 2015). Formerly part of the dukedom of Normandy, they have owed allegiance to England since the Norman Conquest in 1066, and are now classed as Crown dependencies.
Definition of Channel Islands in US English:
Channel Islands
proper noun
1A group of islands in the English Channel off the northwestern coast of France, classed as British Crown dependencies; population 164,000 (estimated 2015). The largest are Jersey, Guernsey, and Alderney.
2
another name for the Santa Barbara Islands in California