alighten vs irradiate

alighten

verb
  • To make light; to illuminate or brighten. 

  • To lighten; to reduce in weight or heaviness. 

  • To alight, to dismount or get down from. 

  • To alight; to land, to descend and rest. 

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 alighten and irradiate occurred in a corpus of books? (source: Google Ngram Viewer )