The Collaborative International Dictionary of English v.0.48:

Thrifty \Thrift"y\ (thr[i^]ft"[y^]), a. [Compar. Thriftier;
   superl. Thriftiest.]
   1. Given to, or evincing, thrift; characterized by economy
      and good menegement of property; sparing; frugal.
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            Her chaffer was so thrifty and so new. --Chaucer.
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            I am glad he hath so much youth and vigor left, of
            which he hath not been thrifty.       --Swift.
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   2. Thriving by industry and frugality; prosperous in the
      acquisition of worldly goods; increasing in wealth; as, a
      thrifty farmer or mechanic.
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   3. Growing rapidly or vigorously; thriving; as, a thrifty
      plant or colt.
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   4. Secured by thrift; well husbanded. [R.]
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            I have five hundred crowns,
            The thrifty hire I saved under your father. --Shak.
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   5. Well appearing; looking or being in good condition;
      becoming. [Obs.]
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            I sit at home, I have no thrifty cloth. --Chaucer.
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   Syn: Frugal; sparing; economical; saving; careful.
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WordNet (r) 3.0 (2006):

thrifty
    adj 1: careful and diligent in the use of resources [ant:
           wasteful]
    2: mindful of the future in spending money; "careful with money"
       [syn: careful, thrifty]

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "thrifty":
   Scotch, blooming, booming, burgeoning, canny, careful, chary,
   cheap, cheeseparing, conserving, economic, economical, economizing,
   forehanded, foresighted, frugal, growing, labor-saving, miserly,
   money-saving, niggardly, parsimonious, penny-pinching, penny-wise,
   penurious, preserving, prospering, prosperous, provident, prudent,
   prudential, roaring, robust, saving, scrimping, skimping, spare,
   sparing, stingy, thriving, tight-fisted, time-saving, unwasteful