| stiff(adjective, strong, harsh, solid, cruel) |
| dogged(verb, adjective, strong, tough, firm) |
| unwavering(adjective, strong, flat, firm, total) |
| unshakable(adjective, strong, tough, resolute, obstinate) |
| adamant(adjective, strong, hard, tough, flat) |
| decided(verb, adjective, set, firm, intense) |
| tenacious(adjective, clear, strong, tough, severe) |
| persistent(adjective, strong, tough, flat, firm) |
| unfaltering(adjective, strong, complete, warm, firm) |
| persevering(adjective, strong, tough, keen, flat) |
| definite(adjective, good, clear, strong, easy) |
| staunch(adjective, good, clear, strong, tough) |
| indefatigable(adjective, strong, firm, steady, resolute) |
| unflinching(adjective, strong, flat, firm, harsh) |
| steady(adjective, good, strong, easy, severe) |
| unbendable(adjective, resolute, obstinate, uncompromising, unshakeable) |
| tireless(adjective, strong, keen, firm, energetic) |
| unswerving(adjective, strong, tough, firm, total) |
| certain(adjective, good, clear, strong, easy) |
| established(verb, adjective, strong, easy, flat) |