| perish(verb, decline, weaken, lessen, degenerate) |
| pollute(verb, decline, weaken, lessen, degenerate) |
| reach depths(verb, expression, decline, weaken, lessen) |
| sap(verb, decline, weaken, lessen, degenerate) |
| shrivel(verb, decline, weaken, lessen, degenerate) |
| sicken(verb, decline, weaken, lessen, degenerate) |
| sink(verb, decline, weaken, lessen, degenerate) |
| slump(verb, decline, weaken, lessen, degenerate) |
| turn(verb, decline, weaken, lessen, degenerate) |
| wane(verb, decline, weaken, lessen, degenerate) |
| waste away(verb, expression, phrasal verb, decline, weaken) |
| wear away(verb, expression, phrasal verb, decline, weaken) |
| atrophy(verb, decline, degenerate, deteriorate, wane) |
| become rotten |
| canker |
| corrupt |
| fall to pieces(expression, idiom) |
| go to pieces(expression, idiom) |
| mould |
| moulder |