long-standing

形容词 long-standing:

1. having existed or continued for a long time
   同义词：longstanding
2. having existed for a long time
   同义词：longstanding

long-stand.ing

adj.（形容词）
Of long duration or existence:
长久的：持续很长时间的或长期存在的：
例句：
a long-standing friendship.
长久的友谊