The Collaborative International Dictionary of English v.0.48:

Flourish \Flour"ish\, v. i. [imp. & p. p. Flourished; p. pr. &
   vb. n. Flourishing.] [OE. florisshen, flurisshen, OF.
   flurir, F. fleurir, fr. L. florere to bloom, fr. flos,
   floris, flower. See Flower, and -ish.]
   1. To grow luxuriantly; to increase and enlarge, as a healthy
      growing plant; a thrive.
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            A tree thrives and flourishes in a kindly . . .
            soil.                                 --Bp. Horne.
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   2. To be prosperous; to increase in wealth, honor, comfort,
      happiness, or whatever is desirable; to thrive; to be
      prominent and influental; specifically, of authors,
      painters, etc., to be in a state of activity or
      production.
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            When all the workers of iniquity do flourish. --Ps.
                                                  xcii 7
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            Bad men as frequently prosper and flourish, and that
            by the means of their wickedness.     --Nelson.
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            We say
            Of those that held their heads above the crowd,
            They flourished then or then.         --Tennyson.
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   3. To use florid language; to indulge in rhetorical figures
      and lofty expressions; to be flowery.
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            They dilate . . . and flourish long on little
            incidents.                            --J. Watts.
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   4. To make bold and sweeping, fanciful, or wanton movements,
      by way of ornament, parade, bravado, etc.; to play with
      fantastic and irregular motion.
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            Impetuous spread
            The stream, and smoking flourished o'er his head.
                                                  --Pope.
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   5. To make ornamental strokes with the pen; to write
      graceful, decorative figures.
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   6. To execute an irregular or fanciful strain of music, by
      way of ornament or prelude.
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            Why do the emperor's trumpets flourish thus? --Shak.
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   7. To boast; to vaunt; to brag. --Pope.
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The Collaborative International Dictionary of English v.0.48:

Flourish \Flour"ish\, n.; pl. Flourishes.
   1. A flourishing condition; prosperity; vigor. [Archaic]
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            The Roman monarchy, in her highest flourish, never
            had the like.                         --Howell.
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   2. Decoration; ornament; beauty.
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            The flourish of his sober youth
            Was the pride of naked truth.         --Crashaw.
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   3. Something made or performed in a fanciful, wanton, or
      vaunting manner, by way of ostentation, to excite
      admiration, etc.; ostentatious embellishment; ambitious
      copiousness or amplification; parade of words and figures;
      show; as, a flourish of rhetoric or of wit.
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            He lards with flourishes his long harangue.
                                                  --Dryden.
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   4. A fanciful stroke of the pen or graver; a merely
      decorative figure.
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            The neat characters and flourishes of a Bible
            curiously printed.                    --Boyle.
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   5. A fantastic or decorative musical passage; a strain of
      triumph or bravado, not forming part of a regular musical
      composition; a cal; a fanfare.
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            A flourish, trumpets! strike alarum, drums! --Shak.
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   6. The waving of a weapon or other thing; a brandishing; as,
      the flourish of a sword.
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The Collaborative International Dictionary of English v.0.48:

Flourish \Flour"ish\, v. t.
   1. To adorn with flowers orbeautiful figures, either natural
      or artificial; to ornament with anything showy; to
      embellish. [Obs.] --Fenton.
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   2. To embellish with the flowers of diction; to adorn with
      rhetorical figures; to grace with ostentatious eloquence;
      to set off with a parade of words. [Obs.]
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            Sith that the justice of your title to him
            Doth flourish the deceit.             --Shak.
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   3. To move in bold or irregular figures; to swing about in
      circles or vibrations by way of show or triumph; to
      brandish.
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            And flourishes his blade in spite of me. --Shak.
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   4. To develop; to make thrive; to expand. [Obs.]
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            Bottoms of thread . . . which with a good needle,
            perhaps may be flourished into large works. --Bacon.
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WordNet (r) 3.0 (2006):

flourish
    n 1: a showy gesture; "she entered with a great flourish"
    2: an ornamental embellishment in writing
    3: a display of ornamental speech or language
    4: the act of waving [syn: flourish, brandish]
    5: (music) a short lively tune played on brass instruments; "he
       entered to a flourish of trumpets"; "her arrival was greeted
       with a rousing fanfare" [syn: flourish, fanfare,
       tucket]
    v 1: grow vigorously; "The deer population in this town is
         thriving"; "business is booming" [syn: boom, thrive,
         flourish, expand]
    2: make steady progress; be at the high point in one's career or
       reach a high point in historical significance or importance;
       "The new student is thriving" [syn: thrive, prosper, fly
       high, flourish]
    3: move or swing back and forth; "She waved her gun" [syn:
       brandish, flourish, wave]