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.