| forever and a day(expression, idiom, stable, constant, lasting) |
| forever and aye(expression, idiom) |
| forevermore |
| immutable(stable, constant, enduring, lasting, perpetual) |
| imperishable(stable, constant, enduring, lasting, durable) |
| in all ages(expression, idiom) |
| in for the long haul(expression, idiom, stable, constant, lasting) |
| indestructible(stable, constant, enduring, lasting, durable) |
| invariable(stable, constant, enduring, lasting, durable) |
| long-lasting(stable, constant, enduring, lasting, durable) |
| now and forever(expression, idiom) |
| perduring(stable, constant, enduring, lasting, durable) |
| perennial(stable, constant, enduring, lasting, durable) |
| perpetual(stable, constant, enduring, lasting, durable) |
| perpetually |
| persistent(stable, constant, enduring, lasting, durable) |
| set(stable, constant, enduring, lasting, perpetual) |
| set in concrete(expression, stable, constant, enduring, lasting) |
| set in stone(expression, idiom, stable, constant, lasting) |
| steadfast(stable, constant, enduring, lasting, perpetual) |