The Collaborative International Dictionary of English v.0.48:

Maintainer \Main*tain"er\, n.
   One who maintains.
   [1913 Webster]

WordNet (r) 3.0 (2006):

maintainer
    n 1: someone who upholds or maintains; "firm upholders of
         tradition"; "they are sustainers of the idea of democracy"
         [syn: upholder, maintainer, sustainer]

The Free On-line Dictionary of Computing (30 December 2018):

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)


The Free On-line Dictionary of Computing (30 December 2018):

maintainer

        A member of the Debian project who looks
       after a Debian package.