im ‧ per ‧ cep ‧ ti ‧ ble /ˌɪmpəˈseptəb ə l, ˌɪmpəˈseptɪb ə l $ -pər-/ BrE AmE adjective
[ Word Family: noun : ↑ perception , ↑ perceptiveness ; adverb : ↑ perceptibly ≠ ↑ imperceptibly , ↑ perceptively ; adjective : ↑ perceptible ≠ ↑ imperceptible , ↑ perceptive ; verb : ↑ perceive ]
almost impossible to see or notice:
Such changes are imperceptible to even the best-trained eye.
—imperceptibly adverb :
The daylight faded almost imperceptibly into night.
—imperceptibility /ˌɪmpəseptəˈbɪləti, ˌɪmpəseptɪˈbɪləti $ -pər-/ noun [uncountable]