relapse

v. i. [ imp. & p. p. Relapsed p. pr. & vb. n. Relapsing. ] [ L. relapsus, p. p. of relabi to slip back, to relapse; pref. re- re- + labi to fall, slip, slide. See Lapse. ] 1. To slip or slide back, in a literal sense; to turn back. [ Obs. ] Dryden. [ 1913 Webster ]

2. To slide or turn back into a former state or practice; to fall back from some condition attained; -- generally in a bad sense, as from a state of convalescence or amended condition; as, to relapse into a stupor, into vice, or into barbarism; -- sometimes in a good sense; as, to relapse into slumber after being disturbed. [ 1913 Webster ]

That task performed, [ preachers ] relapse into themselves. Cowper. [ 1913 Webster ]

3. (Theol.) To fall from Christian faith into paganism, heresy, or unbelief; to backslide. [ 1913 Webster ]

They enter into the justified state, and so continue all along, unless they relapse. Waterland. [ 1913 Webster ]