The Collaborative International Dictionary of English v.0.48:

Pelagianism \Pe*la"gi*an*ism\, n. [Cf. F. p['e]lagianisme.]
   The doctrines of Pelagius.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Pelagianism
    n 1: the theological doctrine put forward by Pelagius which
         denied original sin and affirmed the ability of humans to
         be righteous; condemned as heresy by the Council of Ephesus
         in 431