imperceptibly vs negligibly

imperceptibly

adv
  • Not noticeably; too small to be detected; too little to be perceived. 

  • Beyond the purview of man; too great and all-encompassing to be perceived. 

negligibly

adv
  • To a degree that is negligible; so small or slight that it may be ignored. 

How often have the words imperceptibly and negligibly occurred in a corpus of books? (source: Google Ngram Viewer )