Namesake

A namesake is a person, place, or thing bearing the name of another. Most commonly, it refers to an individual who is purposely named after another (e.g. John F. Kennedy Jr would be the namesake of John F. Kennedy). In common parlance, it may mean vice-versa (i.e. referring to the entity for which the second entity is named); in such a case, however, the proper term would be "eponym."