| pervert(verb, decline, weaken, degenerate, deteriorate) |
| regress(verb, decline, weaken, degenerate, deteriorate) |
| retrograde(verb, decline, weaken, degenerate, deteriorate) |
| retrogress(verb, decline, weaken, degenerate, deteriorate) |
| rot(verb, decline, fail, lower, weaken) |
| sink(verb, decline, weaken, degenerate, deteriorate) |
| skid(verb, decline, weaken, degenerate, deteriorate) |
| slide(verb, decline, weaken, degenerate, deteriorate) |
| spoil(verb, decline, fail, lower, weaken) |
| undermine(verb, decline, weaken, degenerate, deteriorate) |
| vitiate(verb, decline, weaken, degenerate, deteriorate) |
| weaken(verb, decline, degenerate, deteriorate, decay) |
| wear away(verb, expression, phrasal verb, decline, fail) |
| worsen(verb, decline, weaken, degenerate, deteriorate) |
| break down(verb, expression, decline, reoccur, unsay) |
| breaking down(verb, expression, decline, reoccur, unsay) |
| decrease |
| deteriorated |
| dilapidate(verb, decline, reoccur, unsay, unsaying) |
| downhill |