People or things that have been used for a very long time and that are no longer considered to be useful can be referred to as dead wood .
...the idea that historical linguistics is so much dead wood.
N-UNCOUNT [ disapproval ]
DEAD WOOD
Meaning of DEAD WOOD in English
Collins COBUILD Advanced Learner's English Dictionary. Английский словарь Коллинз COBUILD для изучающих язык на продвинутом уровне. 2006