1. (n.) The act of going backward; decay; degeneration\.

2. (n.) Backward development; a passing from a higher to a lower state of organization or structure, as when an animal, approaching maturity, becomes less highly organized than would be expected from its earlier stages or known relationship. Called also retrograde development, and regressive metamorphism.

Brownian movement about-face advance angular motion ascending ascent axial motion backflowing backing backset backsliding backward motion backward step career climbing comedown course current debasement decadence decadency declension declination decline deformation degeneracy degenerateness degeneration degradation demotion depravation depravedness depreciation derogation descending descent deterioration devolution disenchantment downtrend downturn downward mobility downward motion downward trend drift driftage drop dying ebb ebbing effeteness fading failing failure failure of nerve fall falling-off flight flip-flop flow flux forward motion involution lapse loss of tone mounting oblique motion ongoing onrush passage plunging progress radial motion random motion reaction recession recidivation recidivism reclamation reconversion reentry reflowing refluence reflux regress regression rehabilitation reinstatement relapse restitution restoration retroaction retrocession retroflexion retrogradation retroversion retrusion return returning reversal reverse reversion reverting revulsion rising rollback run rush set setback sideward motion sinking slippage slipping back slump soaring sternway stream subsiding throwback traject trajet trend turn turnabout upward motion wane