vestigial
🇺🇸
/veˈstɪdʒiəl/
🇬🇧
/veˈstɪdʒiəl/
adjective
R
something small and remaining from something larger that was once there
The tiny tail on a human embryo is a vestigial part that we don't need anymore.
人間の胚にある小さな尾は、もう必要のない退化した部分です。
translation
退化した