darkening
Definitions
The process of becoming or making something less bright or darker in color.
The approach of nightfall or the dimming of light.
Examples
The darkening sky signaled that a severe thunderstorm was approaching the valley.
He noticed the darkening of the bruise on his arm as the day progressed.
Synonyms
dimming shadowing clouding obscuring blackening shading gloom
Antonyms
brightening lightening illuminating clearing shining glowing radiating