cock
defect
degenerate
desert
err
fall
fall again into
fall astern
fall away
fall back
fall behind
fall from grace
get behind
go astray
go backwards
go behind
go wrong
have a relapse
jerk back
lapse
lapse back
lose ground
pull back
recede
recidivate
recur to
refall
regress
relapse
retrocede
retroflex
retrograde
retrogress
retrovert
return
return to
reverse
revert
revert to
sink back
slide
slide back
slip
slip back
tergiversate
trip
backslid
backslidden
drop away
drop-off
backslides
backsliding