| impassive(adjective, dull, weak, easy, slow) |
| inattentive(adjective, dull, careless, idle, sluggish) |
| indifferent(adjective, dull, weak, easy, slow) |
| indolent(adjective, dull, careless, relaxed, indifferent) |
| infirm(adjective, dull, weak, easy, slow) |
| laggard(adjective, dull, careless, indifferent, idle) |
| lagging(adjective, dull, careless, idle, sluggish) |
| laid-back(adjective, dull, weak, easy, slow) |
| languishing(adjective, dull, weak, easy, slow) |
| lazy(adjective, dull, weak, easy, slow) |
| leaden(adjective, dull, weak, easy, slow) |
| leisurely(adjective, dull, weak, easy, slow) |
| lifeless(adjective, dull, careless, indifferent, idle) |
| limp(adjective, dull, weak, easy, slow) |
| listless(adjective, dull, quiet, weak, easy) |
| loafing(adjective, dull, careless, idle, sluggish) |
| lulling(adjective, tired, lethargic, sleepy, dazed) |
| lymphatic(adjective, weak, easy, slow, heavy) |
| moony(adjective, dull, weak, easy, slow) |
| napping |