attenuation vs waning

attenuation

noun
  • A gradual diminishing of strength. 

  • A reduction in the level of some property with distance, especially the amplitude of a wave or the strength of a signal. 

  • The reduction of the active principles of medicines to minute doses. 

  • The tapering of a leaf etc to a fine point. 

  • A weakening in the virulence of a pathogen or other microorganism. 

  • A fabrication process in which a material is stretched out into a thin shape. 

  • The proportion of sugar that is converted to ethanol by a yeast. 

waning

noun
  • The fact or act of becoming less or less intense or present; fading. 

  • The fact or act of becoming smaller. 

adj
  • Becoming weaker or smaller. 

  • Of the lunar phase: as it shrinks when viewed from the Earth. 

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