The Collaborative International Dictionary of English v.0.48:

Legal \Le"gal\ (l[=e]"gal), a. [L. legalis, fr. lex, legis, law;
   prob. orig., that which lies or is fixed (cf. L. lectus bed),
   and if so akin to E. lie, law: cf. F. l['e]gal. Cf. Lie to
   be prostrate, Loyal, Leal.]
   1. Created by, permitted by, in conformity with, or relating
      to, law; as, a legal obligation; a legal standard or test;
      a legal procedure; a legal claim; a legal trade; anything
      is legal which the laws do not forbid.
      [1913 Webster]

   2. (Theol.)
      (a) According to the law of works, as distinguished from
          free grace; or resting on works for salvation.
      (b) According to the old or Mosaic dispensation; in
          accordance with the law of Moses.
          [1913 Webster]

   3. (Law) Governed by the rules of law as distinguished from
      the rules of equity; as, legal estate; legal assets.
      --Bouvier. --Burrill.
      [1913 Webster]

   Legal cap. See under Cap.

   Legal tender.
      (a) The act of tendering in the performance of a contract
          or satisfaction of a claim that which the law
          prescribes or permits, and at such time and place as
          the law prescribes or permits.
      (b) That currency, or money, which the law authorizes a
          debtor to tender and requires a creditor to receive.
          It differs in different countries.

   Syn: Lawful; constitutional; legitimate; licit; authorized.
        See Lawful.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Tender \Ten"der\, n.
   1. (Law) An offer, either of money to pay a debt, or of
      service to be performed, in order to save a penalty or
      forfeiture, which would be incurred by nonpayment or
      nonperformance; as, the tender of rent due, or of the
      amount of a note, with interest.
      [1913 Webster]

   Note: To constitute a legal tender, such money must be
         offered as the law prescribes. So also the tender must
         be at the time and place where the rent or debt ought
         to be paid, and it must be to the full amount due.
         [1913 Webster]

   2. Any offer or proposal made for acceptance; as, a tender of
      a loan, of service, or of friendship; a tender of a bid
      for a contract.
      [1913 Webster]

            A free, unlimited tender of the gospel. --South.
      [1913 Webster]

   3. The thing offered; especially, money offered in payment of
      an obligation. --Shak.
      [1913 Webster]
      [1913 Webster]

   Legal tender. See under Legal.

   Tender of issue (Law), a form of words in a pleading, by
      which a party offers to refer the question raised upon it
      to the appropriate mode of decision. --Burrill.
      [1913 Webster]

WordNet (r) 3.0 (2006):

legal tender
    n 1: something that can be used as an official medium of payment
         [syn: tender, legal tender, stamp]

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "legal tender":
   and pence, cash, circulating medium, coinage, coined liberty,
   cold cash, currency, dollars, emergency money, filthy lucre,
   fractional currency, gold, hard cash, hard currency, lucre, mammon,
   managed currency, medium of exchange, mintage, money,
   necessity money, pelf, postage currency, postal currency, pounds,
   scrip, shillings, silver, soft currency, specie, sterling,
   the almighty dollar, the wherewith, the wherewithal