Retrogression

n.	1.	The act of retrograding, or going backward; retrogradation.
	2.	(Biol.) 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.

Noun	1.	retrogression - passing from a more complex to a simpler biological form Synonyms: degeneration
	2.	retrogression - returning to a former state Synonyms: regress, retroversion, regression, reversion

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