The Collaborative International Dictionary of English v.0.48:

Heathendom \Hea"then*dom\ (-d[u^]m), n. [AS.
   h[=ae][eth]end[=o]m.]
   1. That part of the world where heathenism prevails; the
      heathen nations, considered collectively.
      [1913 Webster]

   2. Heathenism. --C. Kingsley.
      [1913 Webster]