1.  deterioration(n = noun.state) impairment - a symptom of reduced quality or strength;
is a kind of decay
has particulars: corrosion, desolation, devastation, decrepitude, dilapidation, wear
Derived forms verb deteriorate₂, verb deteriorate₁

2.  deterioration(n = noun.process) declension, decline in quality, worsening - process of changing to an inferior state;
is a kind of decline, diminution
has particulars: drop-off, falling off, falloff, slack, slump
Derived forms verb deteriorate₂, verb deteriorate₁

N  deterioration, debasement, wane, ebb, recession, retrogradation, decrease, degeneracy, degeneration, degenerateness, degradation, depravation, depravement, devolution, depravity, demoralization, retrogression, masochism, impairment, inquination, injury, damage, loss, detriment, delaceration, outrage, havoc, inroad, ravage, scath, perversion, prostitution, vitiation, discoloration, oxidation, pollution, defoedation, poisoning, venenation, leaven, contamination, canker, corruption, adulteration, alloy, decline, declension, declination, decadence, decadency, falling off, caducity, decrepitude, decay, dilapidation, ravages of time, wear and tear, corrosion, erosion, moldiness, rottenness, moth and rust, dry rot, blight, marasmus, atrophy, collapse, disorganization, delabrement (destruction), aphid, Aphis, plant louse, puceron, vinefretter, vinegrub, wreck, mere wreck, honeycomb, magni nominis umbra, jade, plug, rackabones, skate, tackey, tacky, have seen better days, deteriorate, degenerate, fall off, wane, ebb, retrograde, decline, droop, go down, go downhill, go from bad to worse, go farther and fare worse, jump out of the frying pan into the fire, run to seed, go to seed, run to waste swale, sweal, lapse, be the worse for, sphacelate: break, break down, spring a leak, crack, start, shrivel, fade, go off, wither, molder, rot, rankle, decay, go bad, go to decay, fall into decay, fall into the sear and yellow leaf, rust, crumble, shake, totter, totter to its fall, perish, die, deteriorate, weaken, put back, set back, taint, infect, contaminate, poison, empoison, envenom, canker, corrupt, exulcerate, pollute, vitiate, inquinate, debase, embase, denaturalize, denature, leaven, deflower, debauch, defile, deprave, degrade, ulcerate, stain, discolor, alloy, adulterate, sophisticate, tamper with, prejudice, pervert, prostitute, demoralize, brutalize, render vicious, embitter, acerbate, exacerbate, aggravate, injure, impair, labefy, damage, harm, hurt, shend, scath, scathe, spoil, mar, despoil, dilapidate, waste, overrun, ravage, pillage, wound, stab, pierce, maim, lame, surbate, cripple, hough, hamstring, hit between wind and water, scotch, mangle, mutilate, disfigure, blemish, deface, warp, blight, rot, corrode, erode, wear away, wear out, gnaw, gnaw at the root of, sap, mine, undermine, shake, sap the foundations of, break up, disorganize, dismantle, dismast, destroy, damnify, do one's worst, knock down, deal a blow to, play havoc with, play sad havoc with, play the mischief with, play the deuce with, play the very devil with, play havoc among, play sad havoc among, play the mischief among, play the deuce among, play the very devil among, decimate, Adj, unimproved &c (improve), deteriorated, altered, altered for the worse, injured, sprung, withering, spoiling, on the wane, on the decline, tabid, degenerate, marescent, worse, the worse for, all the worse for, out of repair, out of tune, imperfect, the worse for wear, battered, weathered, weather-beaten, stale, passe, shaken, dilapidated, frayed, faded, wilted, shabby, secondhand, threadbare, worn, worn to a thread, worn to a shadow, worn to the stump, worn to rags, reduced, reduced to a skeleton, far gone, tacky, decayed, moth-eaten, worm-eaten, mildewed, rusty, moldy, spotted, seedy, time-worn, moss-grown, discolored, effete, wasted, crumbling, moldering, rotten, cankered, blighted, tainted, depraved, decrepid, decrepit, broke, busted, broken, out of commission, hors de combat, out of action, broken down, done, done for, done up, worn out, used up, finished, beyond saving, fit for the dust hole, fit for the wastepaper basket, past work, at a low ebb, in a bad way, on one's last legs, undermined, deciduous, nodding to its fall, tottering, past cure, fatigued, retrograde, deleterious, out of the frying pan into the fire, agrescit medendo, what a falling off was there!.

N  relapse, lapse, falling back, retrogradation, deterioration, backsliding, recidivation, recidivism, recidivity, recrudescence.

N  nonincrease, decrease, decrease, diminution, lessening, subtraction, reduction, abatement, declension, shrinking (contraction, ), coarctation, abridgment, extenuation, subsidence, wane, ebb, decline, ebbing, descent, decrement, reflux, depreciation, deterioration, anticlimax, mitigation, unincreased, decreased, decreasing, on the wane, a gilded halo hovering round decay, fine by degrees and beautifully less.

N  stability, immutability, unchangeability unchangeableness, constancy, stable equilibrium, immobility, soundness, vitality, stabiliment, stiffness, ankylosis, solidity, aplomb, establishment, fixture, rock, pillar, tower, foundation, leopard's spots, Ethiopia's skin, permanence, obstinacy, unchangeable, immutable, unaltered, unalterable, not to be changed, constant, permanent, invariable, undeviating, stable, durable, perennial, fixed, steadfast, firm, fast, steady, balanced, confirmed, valid, fiducial, immovable, irremovable, riveted, rooted, settled, established, vested, incontrovertible, stereotyped, indeclinable, tethered, anchored, moored, at anchor, on a rock, rock solid, firm as a rock, firmly seated, firmly established, deep-rooted, ineradicable, inveterate, obstinate, transfixed, stuck fast, aground, high and dry, stranded, stuck, jammed, unremovable, quiescent, deterioration, indefeasible, irretrievable, intransmutable, incommutable, irresoluble, irrevocable, irreversible, reverseless, inextinguishable, irreducible, indissoluble, indissolvable, indestructible, undying, imperishable, incorruptible, indelible, indeciduous, insusceptible, insusceptible of change, Int, stet, littera scripta manet.

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.