abate β If something bad or undesirable abates, it becomes much less strong or severe.
backslide β to lapse into bad habits or vices from a state of virtue, religious faith, etc
cheapen β If something cheapens a person or thing, it lowers their reputation or position.
decay β When something such as a dead body, a dead plant, or a tooth decays, it is gradually destroyed by a natural process.
degenerate β If you say that someone or something degenerates, you mean that they become worse in some way, for example weaker, lower in quality, or more dangerous.
disintegrate β to separate into parts or lose intactness or solidness; break up; deteriorate: The old book is gradually disintegrating with age.
droop β to sag, sink, bend, or hang down, as from weakness, exhaustion, or lack of support.
ebb β the flowing back of the tide as the water returns to the sea (opposed to flood, flow).
fade β to lose brightness or vividness of color.
languish β to be or become weak or feeble; droop; fade.
lapse β an accidental or temporary decline or deviation from an expected or accepted condition or state; a temporary falling or slipping from a previous standard: a lapse of justice.
go to pot β a container of earthenware, metal, etc., usually round and deep and having a handle or handles and often a lid, used for cooking, serving, and other purposes.
go to the dogs β a domesticated canid, Canis familiaris, bred in many varieties.
corrode β If metal or stone corrodes, or is corroded, it is gradually destroyed by a chemical or by rust.
corrupt β Someone who is corrupt behaves in a way that is morally wrong, especially by doing dishonest or illegal things in return for money or power.
decline β If something declines, it becomes less in quantity, importance, or strength.
deprave β Something that depraves someone makes them morally bad or evil.
retrogress β to go backward into an earlier and usually worse condition: to retrogress to infantilism.
slip β to move, flow, pass, or go smoothly or easily; glide; slide: Water slips off a smooth surface.
vitiate β to impair the quality of; make faulty; spoil.
go to pieces β a separate or limited portion or quantity of something: a piece of land; a piece of chocolate.
crumble β If something crumbles, or if you crumble it, it breaks into a lot of small pieces.
degrade β Something that degrades someone causes people to have less respect for them.
undermine β to injure or destroy by insidious activity or imperceptible stages, sometimes tending toward a sudden dramatic effect.
adulterate β If something such as food or drink is adulterated, someone has made its quality worse by adding water or cheaper products to it.
alloy β An alloy is a metal that is made by mixing two or more types of metal together.
break β When an object breaks or when you break it, it suddenly separates into two or more pieces, often because it has been hit or dropped.
debase β To debase something means to reduce its value or quality.
debilitate β If you are debilitated by something such as an illness, it causes your body or mind to become gradually weaker.
decompose β When things such as dead plants or animals decompose, or when something decomposes them, they change chemically and begin to decay.
impair β to make or cause to become worse; diminish in ability, value, excellence, etc.; weaken or damage: to impair one's health; to impair negotiations.
injure β to do or cause harm of any kind to; damage; hurt; impair: to injure one's hand.
mar β to damage or spoil to a certain extent; render less perfect, attractive, useful, etc.; impair or spoil: That billboard mars the view. The holiday was marred by bad weather.