Source : Webster's Revised Unabridged Dictionary (1913)

Maintainer \Main*tain"er\, n.
   One who maintains.

Source : WordNet®

maintainer
     n : someone who upholds or maintains; "firm upholders of
         tradition"; "they are sustainers of the idea of
         democracy" [syn: {upholder}, {sustainer}]

Source : Free On-Line Dictionary of Computing

maintainer
     
         The person responsible for coordinating changes to
        a package of {software} and arranging the distribution of
        updates.  The term usually applies only to {free software}
        where the maintainer (often the author) is doing it as a free
        public service.
     
        (2001-01-27)