DuckCorp Dico

Found one definition

1.                 From The Collaborative International Dictionary of English v.0.48:
                   
   
   
                   
                     
   Howler \Howl"er\, n.
      1. One who howls.
         [1913 Webster]
      2. (Zool.) Any South American monkey of the genus Mycetes.
         Many species are known. They are arboreal in their habits,
         and are noted for the loud, discordant howling in which
         they indulge at night.
         [1913 Webster]