| persistent(adjective, strain, certain, stable, regular) |
| consistent(adjective, change, strain, certain, ordinary) |
| stable(adjective, quiet, soft, gentle, strain) |
| firm(adjective, calm, strong, secure, strain) |
| constant(adjective, calm, change, strong, secure) |
| strong(adjective, strain, firmness, labour, hardiness) |
| unfluctuating(adjective, calm, strong, secure, strain) |
| hard(adjective, strain, firmness, labour, hardiness) |
| sound(adjective, strain, firmness, labour, hardiness) |
| steady(adjective, calm, quiet, strong, secure) |
| stiff(adjective, strain, firmness, labour, hardiness) |
| permanent(adjective, calm, strong, secure, strain) |
| unalterable(adjective, calm, strong, secure, strain) |
| unvarying(adjective, calm, quiet, strong, secure) |
| rigid(adjective, severe, strain, fixed, stiff) |
| unchanging(adjective, change, severe, firm, harsh) |
| perpetual(adjective, strain, steady, stable, regular) |
| steadfast(adjective, calm, strong, secure, strain) |
| lasting(adjective, calm, strong, secure, strain) |
| enduring(adjective, calm, strong, secure, strain) |