imperceptibly
/ˌɪm.pərˈsep.tə.bli/adverb
CEFR C1
Definition
So slowly or slightly that you can't notice it happening.
So slowly or slightly that you can’t notice it happening.
Synonyms
unnoticeably
gradually
So slowly or slightly that you can't notice it happening.
So slowly or slightly that you can’t notice it happening.