The Collaborative International Dictionary of English v.0.48:

Retain \Re*tain"\ (r[-e]*t[=a]n"), v. t. [imp. & p. p.
   Retained (r[-e]*t[=a]nd"); p. pr. & vb. n. Retaining.]
   [F. retainir, L. retinere; pref. re- re- + tenere to hold,
   keep. See Tenable, and cf. Rein of a bridle, Retention,
   Retinue.]
   1. To continue to hold; to keep in possession; not to lose,
      part with, or dismiss; to restrain from departure, escape,
      or the like. "Thy shape invisible retain." --Shak.
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            Be obedient, and retain
            Unalterably firm his love entire.     --Milton.
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            An executor may retain a debt due to him from the
            testator.                             --Blackstone.
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   2. To keep in pay; to employ by a preliminary fee paid; to
      hire; to engage; as, to retain a counselor.
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            A Benedictine convent has now retained the most
            learned father of their order to write in its
            defense.                              --Addison.
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   3. To restrain; to prevent. [Obs.] --Sir W. Temple.
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   Retaining wall (Arch. & Engin.), a wall built to keep any
      movable backing, or a bank of sand or earth, in its place;
      -- called also retain wall.
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   Syn: To keep; hold; restrain. See Keep.
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WordNet (r) 3.0 (2006):

retained
    adj 1: continued in your keeping or use or memory; "in...the
           retained pattern of dancers and guests remembered" [syn:
           retained, maintained]

Moby Thesaurus II by Grady Ward, 1.0:

23 Moby Thesaurus words for "retained":
   alive, conserved, eidetic, enduring, fresh, green, held, held back,
   held in reserve, kept, kept in remembrance, lasting, preserved,
   put by, recalled, recollected, remembered, reserved, saved, spare,
   unforgotten, vivid, withheld