imperceptible vs negligible

imperceptible

adj
  • not perceptible, not detectable, too small in magnitude to be observed 

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

negligible

adj
  • Able to be neglected, ignored or excluded from consideration; too small or unimportant to be of concern. 

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