1.  retrogress(v = verb.change) regress, retrograde - get worse or fall back to a previous condition;
is one way to decline, worsen
Derived forms noun retrogression₂, adjective retrogressive₁
Sample sentences: Something ----s; Somebody ----s; Somebody ----s PP

2.  retrogress(v = verb.body) fall back, lapse, recidivate, regress, relapse - go back to bad behavior; "Those who recidivate are often minor criminals"
is one way to regress, retrovert, return, revert, turn back
Sample sentences: Somebody ----s

   Retrogression. H. Spenser. [1913 Webster]

retrogress, v.intr.
1 go back; move backwards.
2 deteriorate.

Derivative:
retrogressive adj.

Etymology:
RETRO-, after PROGRESS v.