Blacken

1. v. i. To grow black or dark.
2. v. t. To make or render black.
3. v. t. To make dark; to darken; to cloud.
4. v. t. To defame; to sully, as reputation; to make infamous; as, vice blackens the character.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.