| immovable(adjective, mean, strong, hard, secure) |
| stable(adjective, strong, hard, sound, secure) |
| sound(adjective, strong, hard, tough, strain) |
| refractory(adjective, hard, tough, strain, rough) |
| fixed(adjective, mean, strong, hard, sound) |
| set(adjective, strong, hard, secure, tough) |
| resistant(adjective, strong, strain, firm, firmness) |
| steady(adjective, strong, sound, secure, tough) |
| tough(adjective, mean, clear, strong, hard) |
| adamantine(adjective, strong, hard, tough, firm) |
| constant(adjective, strong, secure, strain, flat) |
| unwavering(adjective, strong, secure, flat, firm) |
| insistent(adjective, determined, resolute, obstinate, uncompromising) |
| tight(adjective, close, strong, hard, tough) |
| dogged(adjective, appearance, mean, strong, hard) |
| tenacious(adjective, clear, strong, sound, tough) |
| unalterable(adjective, strain, firmness, labour, hardiness) |
| unshakable(adjective, mean, strong, hard, secure) |
| intractable(adjective, appearance, hard, tough, rough) |
| durable(adjective, strong, sound, tough, strain) |