backslider

from WordNet (r) 3.0 (2006)
backslider
    n 1: someone who lapses into previous undesirable patterns of
         behavior [syn: {recidivist}, {backslider}, {reversionist}]
    
from The Collaborative International Dictionary of English v.0.48
Backslider \Back"slid"er\, n.
   One who backslides.
   [1913 Webster]
    

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