The Collaborative International Dictionary of English v.0.48:

Cocagne \Coc*agne"\, n. [F. cocagne, pays de cocagne; of
   uncertian origin, cf. Prov. F. couque cake, Catal. coca, L.
   coquere to cook; as if the houses in this country were
   covered with cakes. Cf. Cook, Cockney.]
   1. An imaginary country of idleness and luxury.
      [1913 Webster]

   2. The land of cockneys; cockneydom; -- a term applied to
      London and its suburbs. --Smart.
      [1913 Webster]