imperceptibly
1. [ adverb ] in an imperceptible manner or to an imperceptible degree
Synonyms: observably unnoticeably
Examples:

"the power of the Secretary of State in London increased gradually but imperceptibly"

Related terms: perceptibly discernible imperceptible unnoticeable discernible unnoticeable
Similar spelling:   imperceptible
  imperceptibility
  imperatively
  impermissibly
  imperfective
  imperfection
  impertinently
  imperative
  impermissible
  impertinent
  imperforate
  imperfectibility