Definitions
1.VerbTo frown; to look sullen.
2.VerbTo be dark, gloomy, and threatening, as clouds; of the sky: to be covered with dark and threatening clouds; to show threatening signs of approach, as a tempest.
3.NounA frown, a scowl; an angry or sullen look.
4.NounOf the sky, the weather, etc.: a dark, gloomy, and threatening appearance.