whiten

/ˈwaɪtən/
verb
  1. To make something white or whiter, or to become white or whiter.
    • His knuckles whitened as he gripped the railing tightly.
    • The sun will whiten the fabric if you leave it outside too long.
    • You can whiten your teeth with a special toothpaste.
What does "whiten" mean? | whatsthatwordmean | whatsthatwordmean