The Collaborative International Dictionary of English v.0.48:

Keynesianism \Keynesianism\ adj.
   the macroeconomic theories and politico-economic policies of
   British economist John Maynard Keynes (1883-1946) and his
   followers; -- used especially in reference to their advocacy
   of governmental action to maintain low unemployment through
   government spending. See Keynes.
   [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

Keynesianism
    n 1: the economic theories of John Maynard Keynes who advocated
         government monetary and fiscal programs intended to
         stimulate business activity and increase employment