| bound(adjective, set, strong, tough, severe) |
| bovine(adjective, determined, obstinate, uncompromising, unshakeable) |
| brass-bound(adjective, determined, obstinate, uncompromising, unshakeable) |
| emphatic |
| enthusiastic(adjective, keen, intense, energetic, passionate) |
| heroic(adjective, strong, vigorous, noble, bold) |
| implacable(adjective, hard, firm, terrible, determined) |
| industrious(adjective, keen, intense, energetic, lively) |
| iron(adjective, hard, determined, resolution, rigid) |
| liege(adjective, firm, honest, sensible, solid) |
| male(adjective, vigorous, noble, courageous, muscular) |
| perseverant |
| persisting(adjective, determined) |
| pigheaded(adjective, tough, determined, usual, regular) |
| purposive(adjective, intense, deliberate, determined, focused) |
| refractory(adjective, tough, firm, difficult, obstinate) |
| reliable(adjective, calm, close, strong, secure) |
| sincere(adjective, close, set, correct, severe) |
| strict(adjective, close, strong, hard, tough) |
| sure(adjective, calm, close, strong, secure) |