The Collaborative International Dictionary of English v.0.48:

Hayfork \Hay"fork`\ (h[=a]"f[^o]rk`), n.
   A fork for pitching and tedding hay.
   [1913 Webster]

   Horse hayfork, a contrivance for unloading hay from the
      cart and depositing it in the loft, or on a mow, by horse
      power.
      [1913 Webster]

WordNet (r) 3.0 (2006):

hayfork
    n 1: a long-handled fork for turning or lifting hay