imperceptible
🇺🇸
/ˌɪmpərˈseptəbl/
🇬🇧
/ˌɪmpəˈseptəbl/
adjective
R
so small that it's hard to notice or feel
The change in color was so slight that it was almost imperceptible to the naked eye.
颜色的变化如此细微，以至于肉眼几乎察觉不到。
translation
难以察觉