impalpably
/ɪmpɑːlˈpeɪbli/ iMpahL-PLAY-blee
Definitions
1. adverb
in a way that cannot be felt or perceived; imperceptibly
“The temperature dropped impalpably throughout the night.”
2. adverb
in a subtle or intangible manner
“The changes occurred impalpably, making it difficult to pinpoint the exact time.”