whitening

Short definition from Wiktionary

Verb

1. 1
   present participle and gerund of whiten

Noun

1. 1
   A substance, such as a bleach, used to make something white or whiter.
2. 2
   A substance, such as a bleach, used to make something white or whiter: Whiting, a kind of fine white chalk.
3. 3
   The process of making something white or whiter.