Synonyms and related words :
abiding, age-long, aged, ancient, antique, chronic, constant, continuing, diuturnal, durable, enduring, evergreen, hardy, immutable, intransient, inveterate, lasting, long-lasting, long-lived, long-standing, long-term, longeval, longevous, of long duration, of long standing, perdurable, perduring, perennial, permanent, perpetual, persistent, persisting, remaining, sempervirent, stable, staying, steadfast, tough, unfading, vital