What does the word sweeten mean?

Usage examples for sweeten

  1. They vanish when I try to set them down, but they sweeten the leave of the day." – The God of Love by Justin Huntly McCarthy
  2. Remove the interior, or soft crumb, and, at the moment of serving, fill it with the strawberries, which should be picked, and broken up with sufficient sugar to sweeten them nicely. – The Book of Household Management by Mrs. Isabella Beeton