| constant(adjective, strain, still, fixed, firmness) |
| hard-nosed(adjective, mean, strong, hard, tough) |
| resistant(adjective, strong, strain, firm, stiff) |
| steady(adjective, feature, state, characteristic, complete) |
| adamantine(adjective, strong, hard, tough, severe) |
| conservative(adjective, strain, firmness, labour, hardiness) |
| durable(adjective, strong, strain, firm, stiff) |
| tough(adjective, mean, strong, hard, easy) |
| unwavering(adjective, determined, resolute, persistent, constant) |
| fast(adjective, complete, secure, strain, firm) |
| settled(adjective, secure, strain, determined, usual) |
| austere(adjective, strong, hard, tough, severe) |
| solid(adjective, strong, hard, complete, secure) |
| enduring(adjective, strain, firm, fixed, stiff) |
| lasting(adjective, strain, firmness, labour, hardiness) |
| permanent(adjective, strain, firmness, labour, hardiness) |
| perpetual(adjective, strain, firmness, labour, hardiness) |
| exacting(adjective, hard, tough, easy, severe) |
| proof(adjective, strain, firmness, labour, hardness) |
| quiescent(adjective, strain, firmness, labour, hardiness) |