The Collaborative International Dictionary of English v.0.48:

Become \Be*come"\, v. i. [imp. Became; p. p. Become; p. pr.
   & vb. n. Becoming.] [OE. bicumen, becumen, AS. becuman to
   come to, to happen; akin to D. bekomen, OHG.a piqu["e]man,
   Goth. biquiman to come upon, G. bekommen to get, suit. See
   Be-, and Come.]
   1. To pass from one state to another; to enter into some
      state or condition, by a change from another state, or by
      assuming or receiving new properties or qualities,
      additional matter, or a new character.
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            The Lord God . . . breathed into his nostrils the
            breath of life; and man became a living soul. --Gen.
                                                  ii. 7.
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            That error now which is become my crime. --Milton.
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   2. To come; to get. [Obs.]
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            But, madam, where is Warwick then become! --Shak.
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   To become of, to be the present state or place of; to be
      the fate of; to be the end of; to be the final or
      subsequent condition of.
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            What is then become of so huge a multitude? --Sir W.
                                                  Raleigh.
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The Collaborative International Dictionary of English v.0.48:

Becoming \Be*com"ing\, n.
   That which is becoming or appropriate. [Obs.]
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The Collaborative International Dictionary of English v.0.48:

Becoming \Be*com"ing\, a.
   Appropriate or fit; congruous; suitable; graceful; befitting.
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         A low and becoming tone.                 --Thackeray.
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   Note: Formerly sometimes followed by of.
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               Such discourses as are becoming of them.
                                                  --Dryden.
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   Syn: Seemly; comely; decorous; decent; proper.
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WordNet (r) 3.0 (2006):

becoming
    adj 1: according with custom or propriety; "her becoming
           modesty"; "comely behavior"; "it is not comme il faut for
           a gentleman to be constantly asking for money"; "a decent
           burial"; "seemly behavior" [syn: becoming, comely,
           comme il faut, decent, decorous, seemly]
    2: displaying or setting off to best advantage; "a becoming new
       shade of rose"; "a becoming portrait"

Moby Thesaurus II by Grady Ward, 1.0:

114 Moby Thesaurus words for "becoming":
   Junoesque, a propos, ad rem, adapted, advantageous, advisable,
   agreeable, amply endowed, applicable, apposite, appropriate,
   apropos, apt, attractive, beautifying, befitting, bonny, braw,
   built, built for comfort, buxom, callipygian, callipygous, chic,
   civil, comely, comme il faut, condign, conforming, congruous,
   convenient, correct, curvaceous, curvy, decent, decorous, delicate,
   desirable, dovetailing, elegant, enhancing, expedient, fair,
   fashionable, favorable, feasible, felicitous, fetching, fit,
   fitted, fitten, fitting, flattering, fructuous, geared, genteel,
   goddess-like, good, good-looking, goodly, happy, just, just right,
   likely, lovely to behold, meet, meshing, modest, nice,
   on the button, opportune, pat, personable, pleasing, pneumatic,
   politic, presentable, profitable, proper, qualified, recommendable,
   relevant, right, rightful, seasonable, seemly, shapely, sightly,
   slender, sortable, stacked, statuesque, stylish, suitable, suited,
   suiting, tailored, tasteful, timely, to be desired, to the point,
   to the purpose, urbane, useful, well-built, well-favored,
   well-formed, well-made, well-proportioned, well-shaped,
   well-stacked, well-timed, wise, worthwhile