The Collaborative International Dictionary of English v.0.48:

Prosperous \Pros"per*ous\, a. [L. prosperus or prosper,
   originally, answering to hope; pro according to + the root of
   sperare to hope. See Despair.]
   1. Tending to prosperity; favoring; favorable; helpful.
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            A happy passage and a prosperous wind. --Denham.
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   2. Being prospered; advancing in the pursuit of anything
      desirable; making gain, or increase; thriving; successful;
      as, a prosperous voyage; a prosperous undertaking; a
      prosperous man or nation.
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            By moderation either state to bear
            Prosperous or adverse.                --Milton.
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   Syn: Fortunate; successful; flourishing; thriving; favorable;
        auspicious; lucky. See Fortunate.
        [1913 Webster] -- Pros"per*ous*ly, adv. --
        Pros"per*ous*ness, n.
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