The Collaborative International Dictionary of English v.0.48:

parent \par"ent\ (p[^a]r"ent or p[=a]r"ent; 277), n. [L. parens,
   -entis; akin to parere to bring forth; cf. Gr. porei^n to
   give, beget: cf. F. parent. Cf. Part.]
   1. One who begets, or brings forth, offspring; a father or a
      mother.
      [1913 Webster]

            Children, obey your parents in the Lord. --Eph. vi.
                                                  1.
      [1913 Webster]

   2. That which produces; cause; source; author; begetter; as,
      idleness is the parent of vice.
      [1913 Webster]

            Regular industry is the parent of sobriety.
                                                  --Channing.
      [1913 Webster]

   Parent cell. (Biol.) See Mother cell, under Mother,
      also Cytula.

   Parent nucleus (Biol.), a nucleus which, in cell division,
      divides, and gives rise to two or more daughter nuclei.
      See Karyokinesis, and Cell division, under Division.
      [1913 Webster]

The Free On-line Dictionary of Computing (17 December 2009):

parent
mother
predecessor

    The ancestor node in a tree that
   points to the current node (one of its child nodes).

   (2005-09-15)


Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "parent":
   agent, ancestor, ancestorial, ancestral, ancestress, author,
   begetter, beginner, catalyst, causer, creator, effector,
   engenderer, father, fatherlike, fatherly, generator, grandfatherly,
   grandmotherly, grandparent, grandparental, guardian, inspirer,
   instigator, maker, mater, materfamilias, maternal, mother,
   motherlike, motherly, mover, origin, originator, parental, pater,
   paterfamilias, paternal, patriarchal, prime mover, primum mobile,
   procreator, producer, progenitor, progenitress, progenitrix, root,
   sire, source, stepfather, stepmother