From Longman Dictionary of Contemporary Englishcockneycock‧ney, Cockney /ˈkɒkni $ ˈkɑːk-/ noun 1 [countable]SG someone who comes from the east part of London, and who has a particular way of speaking which is typical of working-class people who live there2 [uncountable]SPEAK A LANGUAGE a way of speaking English that is typical of working-class people in the east part of London —cockney adjective She has a broad cockney accent.
Examples from the Corpus
cockney• About this time, there was a family funeral - with all the mock solemnity and grandeur of a cockney day out.• Described as a chirpy cockney who could tell a plausible story.• His cockney friends would have called it honest endeavour in a dishonest world.• A new girl called Laura is in my class she has a real cockney accent and she's hilarious!• That would make Sunday tea a real cockney treat.• Also too often they broke away only to lose the initiative by letting the cockney donkeys get back.• She recognized the typical cockney liveliness of these two girls.Origin cockney (1600-1700) cockney “male chicken's egg, child treated too well, person who lives in a town” ((14-19 centuries)), from cocken “of cocks” + ey “egg” ((11-16 centuries)) (from Old English æg) 