| illness(noun, disorder, weakness, condition, depression) |
| imbecility |
| impairment(noun, weakness, fault, lack, lapse) |
| impassivity |
| impotency |
| impuissance(noun, weak, sick, unhealthy) |
| inanition |
| inclination(noun, weakness, fault, lack, lapse) |
| inconstancy(noun, weakness, fault, lack, lapse) |
| indecision(noun, weakness, fault, lack, lapse) |
| indisposition(noun, disorder, weakness, condition, fault) |
| ineffectiveness(noun, weakness, hopelessness, inability, helplessness) |
| ineffectuality(noun, weakness, hopelessness, inability, helplessness) |
| inertia(noun, weak, sick, unhealthy) |
| instability(noun, weakness, fault, lack, lapse) |
| irresolution(noun, weakness, fault, lack, lapse) |
| labefaction(noun, weak, sick, unhealthy) |
| lack(noun, weakness, fault, lapse, failing) |
| lack of energy(noun, weak, sick, unhealthy) |
| languish(noun, weak, sick, unhealthy) |