allay vs brighten

allay

verb
  • To make quiet or put at rest; to pacify or appease; to quell; to calm. 

  • To alleviate; to abate; to mitigate. 

noun
  • Alleviation; abatement; check. 

brighten

verb
  • To make more cheerful and pleasant; to enliven 

  • To make illustrious, or more distinguished; to add luster or splendor to 

  • To grow bright, or more bright in color; to clear up 

  • To make bright or brighter in color. 

  • To become brighter or more cheerful in mood 

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