The Collaborative International Dictionary of English v.0.48:

Mourner \Mourn"er\ (m[=o]rn"[~e]r), n.
   1. One who mourns or is grieved at any misfortune, as the
      death of a friend.
      [1913 Webster]

            His mourners were two hosts, his friends and foes.
                                                  --Byron.
      [1913 Webster]

   2. One who attends a funeral as a hired mourner.
      [1913 Webster]

            Mourners were provided to attend the funeral.
                                                  --L'Estrange.
      [1913 Webster]

WordNet (r) 3.0 (2006):

mourner
    n 1: a person who is feeling grief (as grieving over someone who
         has died) [syn: mourner, griever, sorrower,
         lamenter]