Barnet/ˈbɑːrnɪt/ Definition 1 of 2Pro Tip 1/3Informal Slang Used casually among friends or in relaxed settings; not for formal occasions. Check out the new style of my barnet! Pro Tip 2/3Cockney Origin Originated in London's East End; part of Cockney rhyming slang. Handy for cultural understanding. Her barnet's so trendy, innit? Pro Tip 3/3British Pop Culture Often used in British films and music, helps in grasping U.K. pop culture references. He's got the same barnet as the Beatles used to have.