| deep-rooted(adjective, calm, strong, solid, steady) |
| definite(adjective, severe, firm, harsh, solid) |
| distant(adjective, tough, firm, fixed, rigid) |
| diurnal(adjective, stable, constant, vast, enduring) |
| do or die(expression, adjective, idiom, tough, firm) |
| dogged(adjective, mean, hard, firm, solid) |
| dried(adjective, set, firm, solid, hardened) |
| dug in(expression, adjective, secure, tough, firm) |
| durable(adjective, calm, strong, secure, firm) |
| enduring(adjective, calm, strong, secure, firm) |
| entrenched(adjective, firm, determined, usual, regular) |
| equable(adjective, calm, strong, secure, firm) |
| even(adjective, calm, strong, secure, firm) |
| everlasting(adjective, stable, constant, vast, enduring) |
| fast(adjective, calm, strong, secure, firm) |
| fixed resistant(expression, adjective, calm, strong, substantial) |
| for keeps(expression, adjective, stable, constant, lasting) |
| forever(adjective, stable, constant, vast, enduring) |
| forever and a day(expression, adjective, idiom, stable, constant) |
| formal(adjective, tough, firm, fixed, distant) |