Webster’s Revised Unabridged Dictionary · 1913
Backslide
Back′slide′ (-slīd′; 277), 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.