The Collaborative International Dictionary of English v.0.48:

Sufficient \Suf*fi"cient\, a. [L. sufficiens, -entis, p. pr. of
   sufficere: cf. F. suffisant. See Suffice.]
   1. Equal to the end proposed; adequate to wants; enough;
      ample; competent; as, provision sufficient for the family;
      an army sufficient to defend the country.
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            My grace is sufficient for thee.      --2 Cor. xii.
                                                  9.
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   2. Possessing adequate talents or accomplishments; of
      competent power or ability; qualified; fit.
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            Who is sufficient for these things?   --2 Cor. ii.
                                                  16.
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   3. Capable of meeting obligations; responsible.
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            The man is, notwithstanding, sufficient . . . I
            think I may take his bond.            --Shak.
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   4. Self-sufficient; self-satisfied; content. [R.]
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            Thou art the most sufficient (I'll say for thee),
            Not to believe a thing.               --Beau. & Fl.
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   Syn: Enough; adequate; competent; full; satisfactory; ample.
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WordNet (r) 3.0 (2006):

sufficient
    adj 1: of a quantity that can fulfill a need or requirement but
           without being abundant; "sufficient food" [ant:
           deficient, insufficient]

Moby Thesaurus II by Grady Ward, 1.0:

77 Moby Thesaurus words for "sufficient":
   OK, acceptable, adequacy, adequate, admissible, agreeable,
   all right, ample, authoritative, barely sufficient,
   better than nothing, binding, cogent, comfortable, commensurable,
   commensurate, common, competence, competent, consistent,
   corresponding, decent, due, enough, equal to, fair,
   fair to middling, fairish, fit, good, good enough, goodish, just,
   lawful, legal, legitimate, logical, minimal, minimum, moderate,
   not amiss, not bad, not half bad, not so bad, okay, passable,
   pleasing, plenteous, plentiful, plenty, plenty good enough,
   presentable, pretty good, proportionable, proportionate,
   respectable, satisfactory, satisfying, self-consistent, solid,
   sound, substantial, sufficiency, sufficient for, sufficing,
   suitable, tidy, tolerable, unexceptionable, unexceptional,
   unobjectionable, up to, valid, weighty, well-founded,
   well-grounded, workmanlike