| enduring(adjective, calm, strong, secure, tough) |
| tenable(adjective, reasonable, strain, sensible, rational) |
| abundant(adjective, strain, firmness, greatness, labour) |
| constant(adjective, calm, strong, secure, tough) |
| permanent(adjective, strain, firmness, labour, hardiness) |
| unyielding(adjective, strong, hard, tough, strain) |
| impregnable(adjective, reasonable, strain, firm, true) |
| invariable(adjective, strain, firmness, labour, hardiness) |
| proof(adjective, calm, strain, restrained, short) |
| resistant(adjective, strain, firmness, labour, hardiness) |
| self-contained(adjective, strain, firmness, labour, hardiness) |
| settled(adjective, strong, secure, easy, strain) |
| stabile(adjective, calm, strong, secure, strain) |
| stationary(adjective, strain, firmness, labour, hardiness) |
| unalterable(adjective, strain, firmness, labour, hardiness) |
| well-established(adjective, strain, firmness, labour, hardiness) |
| long-standing(adjective, strain, firmness, labour, hardiness) |
| perpetual(adjective, strain, firmness, labour, hardiness) |
| rock-solid(adjective, hard, strain, firmness, compact) |
| tolerant(adjective, strain, sensible, rational, intelligent) |