Source : Webster's Revised Unabridged Dictionary (1913)

Backslide \Back`slide"\, v. i. [imp. {Backslid}; p. p.
   {Backslidden}, {Backslid}; p. pr. & vb. n. {Backsliding}.]
   [Back, adv. + slide.]
   To slide back; to fall away; esp. to abandon gradually the
   faith and practice of a religion that has been professed.

Backsliding \Back"slid"ing\, a.
   Slipping back; falling back into sin or error; sinning.

         Turn, O backsliding children, saith the Lord. --Jer.
                                                  iii. 14.

Backsliding \Back"slid"ing\, n.
   The act of one who backslides; abandonment of faith or duty.

         Our backslidings are many.               --Jer. xiv. 7.

Source : WordNet®

backsliding
     n : a failure to maintain a higher state [syn: {lapse}, {lapsing},
          {relapse}, {relapsing}, {reversion}, {reverting}]