1.  regressive(a = adj.all) - (of taxes) adjusted so that the rate decreases as the amount of income increases;
Antonym: progressive

2.  regressive(a = adj.all) - opposing progress; returning to a former less advanced state;
Antonym: progressive
Derived form verb regress₃

1.  Passing back; returning. [1913 Webster]

2.  Characterized by retrogression; retrogressive. [1913 Webster]

regressive, adj.
1 regressing; characterized by regression.
2 (of a tax) proportionally greater on lower incomes.

Derivative:
regressively adv. regressiveness n.

N  reversion, return, revulsion, turning point, turn of the tide, status quo ante bellum, calm before a storm, alternation, inversion, recoil, retreat, regression, retrogression, restoration, relapse, recidivism, atavism, vicinism, reverting, regressive, revulsive, reactionary, retrorse, a rebours.

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.