Definition of cocky:
(n) :
abbreviation of
cockatoo, especially when talking to such a bird, as in "hello cocky"; a
farmer
"2005: Visit the local store at Coles Bay and you're greeted by a talking cocky called Jim. — Australian Broadcasting Commission, The World Today program, Town seeks environmental accreditation, 5 August 2005"
(adj) :
overly self-confident up to a point where you're kidding yourself of your abilities