Definitions for "Redden"
To grow or become red; to blush.
turn red, as if in embarrassment or shame; "The girl blushed when a young man whistled as she walked by"
Keywords:  sky, redder, sun, turn, setting
make red; "The setting sun reddened the sky"
turn red or redder; "The sky reddened"
Keywords:  color
To make red or somewhat red; to give a red color to.