Source : Webster's Revised Unabridged Dictionary (1913)

Redden \Red"den\, v. i.
   To grow or become red; to blush.

         Appius reddens at each word you speak.   --Pope.

         He no sooner saw that her eye glistened and her cheek
         reddened than his obstinacy was at once subbued. --Sir
                                                  W. SCott.

Redden \Red"den\ (r?d"d'n), v. t. [imp. & p. p. {Reddened}
   (-d'nd); p. pr. & vb. n. {Reddening}.] [From {Red}, a.]
   To make red or somewhat red; to give a red color to.

Source : WordNet®

redden
     v 1: turn red, as if in embarrassment or shame; "The girl blushed
          when a young man whistled as she walked by" [syn: {blush},
           {crimson}, {flush}]
     2: make red; "The setting sun reddened the sky"
     3: turn red or redder; "The sky reddened"