Whitener

noun

1. One who or that which bleaches, or makes white; especially, some chemical or other agent used for bleaching or cleaning very perfectly.
2. One who, or that which, whitens; a bleaching agent; a bleach; a bleacher; a blancher; a whitewasher.
3. A chemical used as an adjunct to laundering white cloth, which makes white cloth appear whiter. A bluing agent.
4. Any substance used to whiten something; a bleach.
5. A person employed to whiten or bleach.