To slip or slide back, in a literal sense; to turn
back.

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.

To fall from Christian faith into paganism, heresy, or
unbelief; to backslide.

A sliding or falling back, especially into a former bad
state, either of body or morals; backsliding; the state of having
fallen back.