Also coddy-moddy gull. A (young) gull; esp. a (young) common gull, Larus canus, or black-headed gull, Chroicocephalus ridibundus.

The young of any kind of gull.

a pale gull, Larus glaucoides, which breeds in Arctic Canada and Greenland, and overwinters chiefly in Iceland, the British Isles, and North America.

In extended use: something resembling or reminiscent of a powder puff (of the older, fluffy variety) in form or appearance.