a. Marked by a relapse; falling back; tending to return to a former worse state. [ 1913 Webster ]

Relapsing fever (Med.), an acute, epidemic, contagious fever, which prevails also endemically in Ireland, Russia, and some other regions. It is marked by one or two remissions of the fever, by articular and muscular pains, and by the presence, during the paroxism of spiral bacterium (Spirochaete) in the blood. It is not usually fatal. Called also famine fever, and recurring fever. [ 1913 Webster ]

a. Not liable to relapse; secure. Dr. H. More. [ 1913 Webster ]

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 ]

n. [ For sense 2 cf. F. relaps. See Relapse, v. ] 1. A sliding or falling back, especially into a former bad state, either of body or morals; backsliding; the state of having fallen back. [ 1913 Webster ]

Alas! from what high hope to what relapse
Unlooked for are we fallen! Milton. [ 1913 Webster ]

2. One who has relapsed, or fallen back, into error; a backslider; specifically, one who, after recanting error, returns to it again. [ Obs. ] [ 1913 Webster ]

n. One who relapses. Bp. Hall. [ 1913 Webster ]