Literally, a person born within earshot of the bells of St Mary-le-Bow church in what is now the City of London. However, technically speaking there can be no cockneys born after 1945 since the bells were destroyed by German bombs during WWII.

Today the term has expanded to encompass not only those from East London specifically but from London in general. The latter tends to be attributed by non-Londoners, stemming from their ignorance of the true meaning of the word.

when you're hungover as shit after a spending a night drunk as a skunk

Person from the East End of London. Supposedly 'born with the sound of bow-bells'. When I used to live in Houghton Regis there were some next door, and they talked and acted nothing like the ones in Eastenders (most of whom are posh actors trying to sound working class). And let's be honest, a lot of TV producers are lovies and darlings who seem to think working class people (especially cockneys) are automatically criminals. Alright, I'm sure there are criminals in the East End. But thanks to a succession of useless, soft-head, corrupt UK governments, there are bloody villains everywhere you go in Britain. Counties around the south of England tend of be full of 'mockneys' - total arseholes who think putting on a fake cockney accent makes them sound hard (but don't tell their mummies).

person from london's east end.
rhyming slang used in london's east end

Someone born within the sound of Bow Bells in London.

the best accent ever!

The dialect anyone speaks while performing fellatio.