| sluggish(adjective, dull, hard, weak, easy) |
| weighty(adjective, hard, difficult, heavy, complex) |
| oppressive(adjective, hard, difficult, heavy, complex) |
| ponderous(adjective, hard, difficult, heavy, complex) |
| dull(adjective, quiet, colour, severe, flat) |
| languorous(adjective, action, dull, hard, weak) |
| burdensome(adjective, hard, difficult, heavy, complex) |
| lumpish(adjective, hard, difficult, slow, complex) |
| plodding(adjective, hard, difficult, complex) |
| gray(noun, adjective, dull, gloomy, grim) |
| grey(adjective, dull, colour, lead, mousy) |
| massive(adjective, hard, difficult, heavy, complex) |
| sad(adjective, hard, difficult, complex) |
| stodgy(adjective, hard, difficult, complex) |
| grave(adjective, hard, difficult, gloomy, complex) |
| hefty(adjective, hard, difficult, complex) |
| heavy(adjective, dull, quiet, weak, easy) |
| backbreaking(adjective, hard, difficult, complex) |
| hard(adjective, difficult, complex) |
| laborious(adjective, hard, difficult, complex) |