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.
顏色的變化如此細微，以至於肉眼幾乎察覺不到。
translation
難以察覺