darken vs irradiate

darken

verb
  • To make dark or darker by reducing light. 

  • To become gloomy, darker in mood. 

  • To render gloomy, darker in mood. 

  • To cloud, obscure, or perplex; to render less clear or intelligible. 

  • To become dark or darker (having less light). 

  • To make dark or darker in colour. 

  • To blind, impair the eyesight. 

  • To become dark or darker in colour. 

  • To be blinded, lose one’s eyesight. 

  • To make foul; to sully; to tarnish. 

  • To get dark (referring to the sky, either in the evening or as a result of cloud). 

irradiate

verb
  • To illuminate; to brighten; to shine light on. 

  • To radiate, shed, or diffuse. 

  • To emit rays; to shine. 

  • To animate by heat or light. 

  • To treat (food) with ionizing radiation in order to destroy bacteria. 

  • To decorate with shining ornaments. 

  • To enlighten intellectually; to illuminate. 

  • To treat (a tumour or cancerous growth) with radiation. 

adj
  • Illuminated; irradiated; made brilliant or splendid. 

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