The Collaborative International Dictionary of English v.0.48:

Crown \Crown\ (kroun), v. t. [imp. & p. p. Crowned (kround);
   p. pr. & vb. n. Crowning.] [OE. coronen, corunen, crunien,
   crounien, OF. coroner, F. couronner, fr. L. coronare, fr.
   corona a crown. See Crown, n.]
   1. To cover, decorate, or invest with a crown; hence, to
      invest with royal dignity and power.
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            Her who fairest does appear,
            Crown her queen of all the year.      --Dryden.
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            Crown him, and say, "Long live our emperor." --Shak.
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   2. To bestow something upon as a mark of honor, dignity, or
      recompense; to adorn; to dignify.
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            Thou . . . hast crowned him with glory and honor.
                                                  --Ps. viii. 5.
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   3. To form the topmost or finishing part of; to complete; to
      consummate; to perfect.
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            Amidst the grove that crowns yon tufted hill.
                                                  --Byron.
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            One day shall crown the alliance.     --Shak.
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            To crown the whole, came a proposition. --Motley.
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   4. (Mech.) To cause to round upward; to make anything higher
      at the middle than at the edges, as the face of a machine
      pulley.
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   5. (Mil.) To effect a lodgment upon, as upon the crest of the
      glacis, or the summit of the breach.
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   To crown a knot (Naut.), to lay the ends of the strands
      over and under each other.
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WordNet (r) 3.0 (2006):

crowning
    adj 1: representing a level of the highest possible achievement
           or attainment; "the crowning accomplishment of his
           career"
    2: forming or providing a crown or summit; "the crowning star on
       a Christmas tree"; "her hair was her crowning glory"

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "crowning":
   arch, banner, capital, capping, cardinal, central, champion, chief,
   closing, completing, completive, completory, concluding,
   conclusive, consummating, consummative, consummatory, culminating,
   culminative, dominant, ending, final, finalizing, finishing, first,
   focal, foremost, fulfilling, great, heading, headmost, hegemonic,
   last, leading, magisterial, main, master, outtopping, overruling,
   overtopping, paramount, perfecting, perfective, predominant,
   preeminent, preponderant, prevailing, primal, primary, prime,
   principal, ranking, ruling, sovereign, star, stellar, supereminent,
   terminal, terminating, terminative, topflight, topping, ultimate