| never-failing(adjective, strong, complete, flat, firm) |
| notable(adjective, great, extraordinary, outstanding, remarkable) |
| obdurate(adjective, strong, flat, certain, determined) |
| of long standing(expression, idiom, familiar, established, long-established) |
| outliving |
| overlong(adjective, great, high, constant, abundant) |
| perduring(tough, stable, sturdy, constant, lasting) |
| perseverant |
| pertinacious |
| philosophical(adjective, calm, quiet, gentle, persistent) |
| prolonging(verb, increase, line, extension, persistence) |
| relentless(adjective, determined, steady, resolute, persistent) |
| reliable(adjective, calm, close, strong, secure) |
| residing(verb, living) |
| resisting |
| rooted(adjective, certain, limited, definite, persistent) |
| self-controlled(adjective, calm, cool, tolerant, patient) |
| stalwart(adjective, calm, strong, sound, secure) |
| standing(noun, adjective, strength, ability, resolution) |
| static(adjective, quiet, flat, indifferent, fixed) |