alighten vs set down

alighten

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

  • To make light; to illuminate or brighten. 

  • To lighten; to reduce in weight or heaviness. 

  • To alight, to dismount or get down from. 

set down

verb
  • To land. 

  • To fix; to establish; to ordain. 

  • To place, especially on the ground or a surface; to cease carrying; to deposit; to allow passengers to alight. 

  • To write. 

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