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.