| strong(adjective, tough, strain, determined, stiff) |
| stiff(adjective, strong, strain, firmness, tight) |
| stable(adjective, strain, firmness, labour, hardiness) |
| hard(adjective, strain, firmness, labour, hardiness) |
| firm(noun, adjective, strain, firmness, labour) |
| flexible(adjective, strong, tough, soft, flexible) |
| elastic(adjective, strong, tough, soft, bright) |
| durable(adjective, strain, firmness, labour, hardiness) |
| resistant(adjective, strong, tough, strain, stiff) |
| robust(adjective, strain, firmness, labour, hardiness) |
| stout(adjective, strain, firmness, labour, hardiness) |
| buoyant(adjective, feature, state, strong, light) |
| tolerant(adjective, feature, state, strain, trait) |
| fast(adjective, strain, firmness, labour, hardiness) |
| refractory(adjective, strain, firmness, labour, hardiness) |
| springy(adjective, strong, soft, loose, flexible) |
| tenable(adjective, strain, firmness, labour, hardiness) |
| rock-solid(adjective, strain, firmness, labour, hardiness) |
| substantial(adjective, strain, firmness, labour, hardiness) |
| immune(adjective, strain, firmness, unaffected, labour) |