1.  regress(n = noun.cognition) reasoning backward - the reasoning involved when you assume the conclusion is true and reason backward to the evidence;
is a kind of abstract thought, logical thinking, reasoning

2.  regress(n = noun.act) regression, retrogression, retroversion, reversion - returning to a former state;
is a kind of reversal
Derived form verb regress₂

1.  regress(v = verb.change) - go back to a statistical means;
is one way to change
Sample sentences: Something ----s

2.  regress(v = verb.change) retrovert, return, revert, turn back - go back to a previous state; "We reverted to the old rules"
is one way to change by reversal, reverse, turn
Derived forms noun regress₂, noun regression₄
Sample sentences: Something ----s; Somebody ----s; Something is ----ing PP; Somebody ----s PP

3.  regress(v = verb.change) retrograde, retrogress - get worse or fall back to a previous condition;
is one way to decline, worsen
Antonym: progress
Derived form adjective regressive₂
Sample sentences: Something ----s; Somebody ----s; Somebody ----s PP

4.  regress(v = verb.body) fall back, lapse, recidivate, relapse, retrogress - 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

1.  The act of passing back; passage back; return; retrogression. “The progress or regress of man”. F. Harrison. [1913 Webster]

2.  The power or liberty of passing back. Shak. [1913 Webster]

   To go back; to return to a former place or state. Sir T. Browne. [1913 Webster]

regress, v. & n.
--v.
1 intr. move backwards, esp. (in abstract senses) return to a former state.
2 intr. & tr. Psychol. return or cause to return mentally to a former stage of life, esp. through hypnosis or mental illness.
--n.
1 the act or an instance of going back.
2 reasoning from effect to cause.

Etymology:
ME (as n.) f. L regressus f. regredi regress- (as RE-, gradi step)

VB  revert, turn back, regress, relapse, recoil, retreat, restore, undo, unmake, turn the tide, roll back the tide, turn the scale, tip the scale.

N  regress, regression, retrocession, retrogression, retrograduation, retroaction, reculade, retreat, withdrawal, retirement, remigration, recession, recess, crab-like motion, refluence, reflux, backwater, regurgitation, ebb, return, resilience reflection, reflexion (recoil), flip-flop, volte-face, counter motion, retrograde motion, backward movement, motion in reverse, counter movement, counter march, veering, tergiversation, recidivation, backsliding, fall, deterioration, recidivism, recidivity, reversal, relapse, turning point, receding, retrograde, retrogressive, regressive, refluent, reflex, recidivous, resilient, crab-like, balky, reactionary, back, backwards, reflexively, to the right about, a reculons, a rebours, revenons a nos moutons, as you were.

infinite regress