| slide(noun, verb, drop, decline, fall) |
| slump(noun, verb, drop, decline, settle) |
| suffer(verb, weaken, degenerate, deteriorate, revert) |
| turn back(verb, expression, phrasal verb, weaken, degenerate) |
| vestige(back, slow, backward, reverse direction) |
| wilt(verb, decline, fail, halt, lower) |
| abate(verb, drop, decline, reduce, settle) |
| about-face(verb, move, change, push, return) |
| apostasy |
| be overcome(verb, expression, idiom, weaken, degenerate) |
| be overtaken(verb, expression, idiom, weaken, degenerate) |
| dawdle |
| diminish(verb, drop, decline, reduce, settle) |
| disimprove(verb, drop, reduce, fall, fail) |
| droop(verb, drop, decline, settle, fall) |
| dwindle(verb, drop, decline, reduce, settle) |
| fall behind(verb, expression, phrasal verb) |
| flag(verb, drop, decline, settle, fall) |
| get back |
| illness(noun, disease, sickness, spell, complaint) |