Source : Webster's Revised Unabridged Dictionary (1913)

Namesake \Name"sake`\, n. [For name's sake; i. e., one named for
   the sake of another's name.]
   One that has the same name as another; especially, one called
   after, or named out of regard to, another.

Source : WordNet®

namesake
     n : a person with the same name as another