Synonyms of long-standing in English:

long-standing


See US English definition of long-standing

See UK English definition of long-standing

See Spanish definition of antiguo

adjective

1‘a long-standing friendship’

SYNONYMS
well established, long-established, established, fixed
time-honoured, time-hallowed
abiding, enduring, long-lived, surviving, persistent, prevailing, durable, perennial
firm, constant, deep-rooted, steady, stable, staunch, long-term
ANTONYMS

new, recent