Synonyms for Brighten:

n.

glow, thrive on, rejoice, jump for joy, improve, shade, rejoice in, live happily ever after, look forward to, be happy for someone, treasure. perk up, tint, redden, dye, respray, paint, color. happy, animate. brighten (noun)
lighten up, lighten, clear, clear up, light up.

v.

brighten (verb)
illuminate, shine, illumine, lighten, intensify, burnish.
change (verb)
lighten up, lighten.
cheer (verb)
encourage, hearten, gladden, please, console, cheer, inspire, enliven.
make happy, feel better (verb)
encourage, perk up, gladden, improve, hearten, cheer.
make shine or glow (verb)
polish, intensify, enliven, lighten, light up, illuminate, burnish, clear up, illumine.
weather (verb)
light up, clear, clear up.

Other synonyms:

respray, rejoice in, blacken, redden, look forward to. dye. treasure, animate, bleach. tint, paint, mellow, bleed. color. gray. change. cheer
perk up.
lighten
lighten.
light up
illumine.
please
gladden.
Other relevant words:
gray, color, rejoice, light up, clear, clear up, treasure, glow, lighten up, respray, polish, bleed, animate, perk up, mellow, improve, change.

Usage examples for brighten

  1. I always brighten up in your house." – The Twilight of the Souls by Louis Couperus
  2. There, as the peaks of the mountains brighten they are seen to have great faces. – The Little Dream (Second Series Plays) by John Galsworthy Last Updated: February 10, 2009
  3. Mercy's color rose; Mercy's eyes began to brighten – The New Magdalen by Wilkie Collins