| sticky(adjective, hard, difficult, complex) |
| implacable(adjective, characteristic, appearance, quality, mean) |
| intricate(adjective, hard, difficulty, difficult, complex) |
| knotted(adjective, hard, difficulty, difficult, complex) |
| knotty(adjective, hard, difficulty, difficult, complex) |
| labyrinthine(adjective, hard, difficulty, difficult, complex) |
| painful(adjective, hard, tough, difficult, harsh) |
| plodding(adjective, hard, difficult, complex) |
| complicated(adjective, hard, difficulty, difficult, complex) |
| rebellious(adjective, characteristic, quality, tough, firm) |
| rough(adjective, strong, hard, tough, difficult) |
| unmanageable(adjective, characteristic, quality, tough, difficulty) |
| steadfast(adjective, characteristic, quality, strong, secure) |
| froward(adjective, ornery, attitude, determination, archaic) |
| grievous(adjective, hard, tough, difficult, harsh) |
| resistant(adjective, characteristic, quality, hard, determined) |
| resolved(adjective, characteristic, quality, firm, deliberate) |
| thorny(adjective, hard, difficulty, difficult, complex) |
| trying(adjective, hard, difficulty, difficult, complex) |
| bloody-minded(adjective, characteristic, quality, resistance, disposition) |