The Collaborative International Dictionary of English v.0.48:

Conditional \Con*di"tion*al\, a. [L. conditionalis.]
   1. Containing, implying, or depending on, a condition or
      conditions; not absolute; made or granted on certain
      terms; as, a conditional promise.
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            Every covenant of God with man . . . may justly be
            made (as in fact it is made) with this conditional
            punishment annexed and declared.      --Bp.
                                                  Warburton.
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   2. (Gram. & Logic) Expressing a condition or supposition; as,
      a conditional word, mode, or tense.
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            A conditional proposition is one which asserts the
            dependence of one categorical proposition on
            another.                              --Whately.
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            The words hypothetical and conditional may be . . .
            used synonymously.                    --J. S. Mill.
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The Collaborative International Dictionary of English v.0.48:

Conditional \Con*di"tion*al\, n.
   1. A limitation. [Obs.] --Bacon.
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   2. A conditional word, mode, or proposition.
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            Disjunctives may be turned into conditionals. --L.
                                                  H. Atwater.
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WordNet (r) 3.0 (2006):

conditional
    adj 1: qualified by reservations
    2: imposing or depending on or containing a condition;
       "conditional acceptance of the terms"; "lent conditional
       support"; "the conditional sale will not be complete until
       the full purchase price is paid" [ant: unconditional,
       unconditioned]

Moby Thesaurus II by Grady Ward, 1.0:

79 Moby Thesaurus words for "conditional":
   a fortiori, a posteriori, a priori, acceptable, accidental,
   adventitious, aleatory, analytic, at issue, casual, categorical,
   circumstantial, conditioned, condonable, contingent, deductive,
   defensible, dependent, depending, dialectic, discursive,
   enthymematic, epagogic, excusable, fixed, formal, fortuitous,
   given, hypothetical, iffy, in question, in suspense,
   in the balance, incidental, inductive, inessential, inferential,
   limited, maieutic, modal, modified, nonessential, obscure,
   occasional, open, pendent, pending, problematic, provisional,
   provisory, qualified, questionable, relative, reliant, restricted,
   soritical, specificative, specified, stated, stipulated,
   stipulatory, suspenseful, syllogistic, synthetic, tenable,
   tentative, tolerable, uncertain, uncounted, undecided,
   undetermined, unessential, unestablished, unfixed, unsettled,
   untold, up for grabs, vindicable, warrantable