The Collaborative International Dictionary of English v.0.48:

Foolery \Fool"er*y\, n.; pl. Fooleries.
   1. The practice of folly; the behavior of a fool; foolish
      behavior; absurdity.
      [1913 Webster]

            Folly in fools bears not so strong a note,
            As foolery in the wise, when wit doth dote. --Shak.
      [1913 Webster]

   2. An act of folly or weakness; a foolish practice; something
      absurd or nonsensical.
      [1913 Webster]

            That Pythagoras, Plato, or Orpheus, believed in any
            of these fooleries, it can not be suspected. --Sir
                                                  W. Raleigh.
      [1913 Webster]

WordNet (r) 3.0 (2006):

foolery
    n 1: foolish or senseless behavior [syn: folly, foolery,
         tomfoolery, craziness, lunacy, indulgence]