imperceptible
im‧per‧cep‧ti‧ble /ˌɪmpəˈseptəbəl, ˌɪmpəˈseptɪbəl $ -pər-/
adjective
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]
im‧per‧cep‧ti‧ble /ˌɪmpəˈseptəbəl, ˌɪmpəˈseptɪbəl $ -pər-/
adjective Word Family: noun: perception, perceptiveness; adverb: perceptibly ≠ imperceptibly, perceptively; adjective: perceptible ≠ imperceptible, perceptive; verb: perceive
almost impossible to see or notice: —imperceptibly adverb:
—imperceptibility /ˌɪmpəseptəˈbɪləti, ˌɪmpəseptɪˈbɪləti $ -pər-/ noun [uncountable]