imperceptibly

adv

imperceptibly

adv

Etymology From imperceptible + -ly.

1

Not noticeably; such that it cannot be detected, through being too small or too fast, etc.

No one noticed that he had moved imperceptibly backwards.
It often happens that the most important results in the natural world are brought about by causes which operate silently, if not imperceptibly.1838, William Andrus Alcott, chapter I, in The Young House-keeper: Or, Thoughts on Food and Cookery, third stereotype edition, Boston: George W. Light, page 21:

2 more examples

The moon moved imperceptibly towards setting.1956, Anthony Burgess, Time for a Tiger (The Malayan Trilogy), published 1972, page 154:
Which means that at the moment Raven entered her, a very small hypodermic needle slipped imperceptibly into the engorged frontal vein of his penis, automatically shooting a cocktail of powerful narcotics and depressants into his bloodstream.1992, Neal Stephenson, Snow Crash, page 358:

Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.