The Collaborative International Dictionary of English v.0.48:

Helot \He"lot\ (?; 277), n. [L. Helotes, Hilotae, pl., fr. Gr.
   E'e`lws and E'elw`ths a bondman or serf of the Spartans; so
   named from 'Elos, a town of Laconia, whose inhabitants were
   enslaved; or perh. akin to e`lei^n to take, conquer, used as
   2d aor. of ?.]
   A slave in ancient Sparta; a Spartan serf; hence, a slave or
   serf.
   [1913 Webster]

         Those unfortunates, the Helots of mankind, more or less
         numerous in every community.             --I. Taylor.
   [1913 Webster]

WordNet (r) 3.0 (2006):

helot
    n 1: (Middle Ages) a person who is bound to the land and owned
         by the feudal lord [syn: serf, helot, villein]