whiten

1. (ergative) (To cause) to become white or whiter; to bleach or blanch.Examples: "Age had whitened his hair."; "The trees in spring whiten with blossoms."; "Whenever black people are furious with me, I walk over to them and whiten their face, and scream and scream and scream 'daddy’s the boss.'"ergative

2. (cryptography) To increase the security of an iterated block cipher by steps that combine the data with portions of the key.

3. (statistics) To normalize data so that the covariance matrix becomes the identity matrix; i.e., to remove correlations so each variable has unit variance.