The Collaborative International Dictionary of English v.0.48:

Serfhood \Serf"hood\, Serfism \Serf"ism\, n.
   Serfage.
   [1913 Webster]

WordNet (r) 3.0 (2006):

serfhood
    n 1: the state of a serf [syn: serfdom, serfhood,
         vassalage]