Definition of blacken verb from the Oxford Advanced American Dictionary
blacken
verb
/ˈblækən/
1[transitive, intransitive]blacken (something)to make something black; to become blackTheir faces were blackened with soot.Smoke had blackened the walls.rows of blackened teeth2[transitive]blacken someone's name/reputation/characterto say unpleasant things that give people a bad opinion of someoneHe accused the newspaper of trying to blacken his name.
