The Collaborative International Dictionary of English v.0.48:

Maintain \Main*tain\, v. t. [imp. & p. p. Maintained; p. pr. &
   vb. n. Maintaining.] [OE. maintenen, F. maintenir,
   properly, to hold by the hand; main hand (L. manus) + F.
   tenir to hold (L. tenere). See Manual, and Tenable.]
   1. To hold or keep in any particular state or condition; to
      support; to sustain; to uphold; to keep up; not to suffer
      to fail or decline; as, to maintain a certain degree of
      heat in a furnace; to maintain a fence or a railroad; to
      maintain the digestive process or powers of the stomach;
      to maintain the fertility of soil; to maintain present
      reputation.
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   2. To keep possession of; to hold and defend; not to
      surrender or relinquish.
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            God values . . . every one as he maintains his post.
                                                  --Grew.
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   3. To continue; not to suffer to cease or fail.
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            Maintain talk with the duke.          --Shak.
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   4. To bear the expense of; to support; to keep up; to supply
      with what is needed.
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            Glad, by his labor, to maintain his life.
                                                  --Stirling.
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            What maintains one vice would bring up two children.
                                                  --Franklin.
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   5. To affirm; to support or defend by argument.
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            It is hard to maintain the truth, but much harder to
            be maintained by it.                  --South.
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   Syn: To assert; vindicate; allege. See Assert.
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WordNet (r) 3.0 (2006):

maintained
    adj 1: kept in good condition [syn: kept up(p), maintained,
           well-kept]
    2: continued in your keeping or use or memory; "in...the
       retained pattern of dancers and guests remembered" [syn:
       retained, maintained]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

MAINTAINED, pleadings. This is a technical word, indispensable in an
indictment for maintenance, which no other word or circumlocution will
supply. 1 Wils. 325.