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]

Moby Thesaurus II by Grady Ward, 1.0:

337 Moby Thesaurus words for "flourish":
   acciaccatura, adjunct, adorn, adornment, advertise, affect, air,
   amplify, appoggiatura, arabesque, arrangement, arrive, asiaticism,
   augment, batten, be energetic, be somebody, be something,
   be vigorous, bear fruit, beauties, betoken, blazon, blazon forth,
   bloom, blossom, blow, bluster, boast, bonus, boom, brag, brandish,
   brandishing, bravura, breathe, brew, brilliancy, bring forth,
   bring forward, bring into view, bring out, bring to maturity,
   bring to notice, bud, burgeon, burst forth, burst with energy,
   burst with health, cadence, cadenza, color, color patterns,
   coloratura, colors, colors of rhetoric, come to fruition,
   convolute, curlicue, cut a dash, cut a figure, dangle, daring,
   dash, decor, decorate, decoration, demonstrate, demonstration,
   develop, device, disclose, display, division, divulge, do well,
   dramatics, dramatize, draw the longbow, eclat, elaborate,
   elaboration, elegant variation, embellish, embellishment, emblazon,
   emblazonment, emblazonry, embody, embroider, embroidery, enact,
   enjoy good health, enrich, etalage, euphuism, evidence, evince,
   exhibit, exhibition, exhibitionism, expand, expose to view,
   express, extempore, extra, extra added attraction, extra dash,
   false front, fanfare, fanfaronade, fare well, fatten, feel fine,
   feel good, festoon, figurative language, figurativeness, figure,
   figure of speech, filigree, filling, fillip, fine writing,
   fioritura, flair, flap, flash, flaunt, flaunting, flight, float,
   floridity, floridness, flourishing, flower, flower arrangement,
   floweriness, flowers of speech, flowery style, flutter, fly, frill,
   fructify, furbelow, furniture arrangement, garnish, garnishment,
   garniture, gasconade, gather, gemmate, germinate, gesturing,
   get ahead, gild, give sign, give token, gleam, glitter, glow, go,
   go great guns, grace, grace note, grow, grow fat, grow rank,
   grow up, have energy, highlight, histrionics, hold up, hot lick,
   hypertrophy, illuminate, illumination, image, imagery, impromptu,
   improvisation, in full swing, incarnate, incidental,
   incidental note, increase, indicate, interpolation, involve,
   keep fit, lagniappe, leaf, leaf out, leave, lick, live,
   load with ornament, long mordent, lushness, luxuriance, luxuriate,
   make a figure, make a splash, make clear, make good, make out,
   make plain, manifest, manifestation, manner of speaking,
   materialize, maturate, mature, mean, mellow, mordent, multiply,
   mushroom, never feel better, nonliterality, nonliteralness,
   ornament, ornamentation, outgrow, overcharge, overdevelop,
   overflow with energy, overgrow, overlay, overload, overrun,
   overtop, padding, pageant, pageantry, parade, passage, perform,
   pralltriller, premium, present, procreate, produce, prosper, puff,
   pullulate, purple passage, purple patches, put forth,
   put forth leaves, put forward, put out buds, reach its season,
   reach maturity, represent, reproduce, reveal, riff, riot, ripe,
   ripen, roll out, root, roulade, run, score, set forth, shake,
   shaking, sham, shine, shoot, shoot up, show, show forth, showiness,
   showing-off, single mordent, something extra, speak for Buncombe,
   spectacle, splash, splurge, sport, spotlight, spring up, sprout,
   sprout up, staginess, stay in shape, stay young, strike root,
   stuffing, succeed, superaddition, swagger, swing, swish, take root,
   theatrics, thrive, token, tower, trick out, trim, trimming, trope,
   trot out, trumpet, trumpet forth, turn, turn of expression, twirl,
   twist, undulate, undulation, unfold, upshoot, upspear, upspring,
   upsprout, vamp, vapor, varnish, vaunt, vegetate, wag, wave,
   wave motion, waving, wax, way of speaking, wear well, wield,
   wigwag, window dressing, wrinkle