What is the meaning of Lour?

To frown; to look sullen.

To 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.

A frown, a scowl; an angry or sullen look.

Of the sky, the weather, etc.: a dark, gloomy, and threatening appearance.

their (third-person plural possessive pronoun)

enough, sufficient

Source: wiktionary.org