Re·lapse v. i. [imp. & p. p. Relapsed p. pr. & vb. n. Relapsing.]
 1. To slip or slide back, in a literal sense; to turn back. [Obs.]
 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.
    That task performed, [preachers] relapse into themselves.   --Cowper.
 3. Theol. To fall from Christian faith into paganism, heresy, or unbelief; to backslide.
    They enter into the justified state, and so continue all along, unless they relapse.   --Waterland.