Idioms and Phrases with look black
Appear threatening or unfavorable, as in The future looked black for Henry after he dropped out of school. This expression employs black in the sense of “boding ill,” a usage dating from about 1700. Also see under dirty look.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.