Source : Webster's Revised Unabridged Dictionary (1913)

Yellow \Yel"low\, v. t. [imp. & p. p. {Yellowed}; p. pr. & vb.
   n. {Yellowing}.]
   To make yellow; to cause to have a yellow tinge or color; to
   dye yellow.

Yellowing \Yel"low*ing\, n.
   The act or process of making yellow.

         Softened . . . by the yellowing which time has given.
                                                  --G. Eliot.