Word Origin & History
cockney
1600, from M.E. cokenei "spoiled child, milksop," orig. cokene-ey "cock's egg" (1362). Most likely disentangling of the etymology is to start from O.E. cocena "cock's egg" -- gen. pl. of coc "cock" + æg "egg" -- medieval term for "runt of a clutch," extended derisively c.1521 to "town dweller," gradually narrowing thereafter to residents of a particular neighborhood in the East End of London. The accent so called from 1890, but speech peculiarities were noted from 17c.
[kok-nee] 
noun, plural -neys, adjective 
) a native or inhabitant of the East End district of London, England, traditionally, one born and reared within the sound of Bow bells.