| inanimate(adjective, dull, sluggish, lifeless, lethargic) |
| inattentive(adjective, dull, careless, relaxed, indifferent) |
| indifferent(adjective, dull, weak, careless, heavy) |
| indolent(adjective, careless, indifferent, apathetic, lethargic) |
| inert(adjective, dull, weak, easy, slow) |
| insouciant(adjective, dull, sluggish, lifeless, lethargic) |
| lackadaisical(adjective, dull, weak, easy, slow) |
| laid-back(adjective, dull, weak, careless, heavy) |
| languid(adjective, dull, weak, easy, slow) |
| languishing(adjective, dull, weak, easy, slow) |
| languorous(adjective, dull, weak, easy, slow) |
| lazy(adjective, dull, weak, easy, slow) |
| leaden(adjective, dull, weak, easy, slow) |
| leisurely(adjective, dull, weak, easy, slow) |
| lethargic(adjective, dull, weak, easy, slow) |
| limp(adjective, dull, weak, easy, slow) |
| listless(adjective, dull, weak, energy, easy) |
| lymphatic(adjective, dull, weak, easy, slow) |
| mopish(adjective, dull, sluggish, lifeless, listless) |
| nebbish(adjective, dull, weak, easy, slow) |