The Collaborative International Dictionary of English v.0.48:

Buxom \Bux"om\, a. [OE. buxum, boxom, buhsum, pliable, obedient,
   AS. b[=o]csum, b[=u]hsum (akin to D. buigzaam blexible, G.
   biegsam); b[=u]gan to bow, bend + -sum, E. -some. See Bow
   to bend, and -some.]
   1. Yielding; pliable or compliant; ready to obey; obedient;
      tractable; docile; meek; humble. [Obs.]
      [1913 Webster]

            So wild a beast, so tame ytaught to be,
            And buxom to his bands, is joy to see. --Spenser.
      [1913 Webster]

            I submit myself unto this holy church of Christ, to
            be ever buxom and obedient to the ordinance of it.
                                                  --Foxe.
      [1913 Webster]

   2. Having the characteristics of health, vigor, and
      comeliness, combined with a gay, lively manner; stout and
      rosy; jolly; frolicsome.
      [1913 Webster]

            A daughter fair,
            So buxom, blithe, and debonair.       --Milton.
      [1913 Webster]

            A parcel of buxom bonny dames, that were laughing,
            singing, dancing, and as merry as the day was long.
                                                  --Tatler.
      [1913 Webster]

   3. having a pronounced womanly shape. [chiefly dialect]

   Syn: bosomy, curvaceous, full-bosomed, sonsie, sonsy,
        voluptuous.
        [WordNet 1.5 +PJC] -- Bux"om*ly, adv. --
        Bux"om*ness, n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

buxom
    adj 1: (of a woman's body) having a large bosom and pleasing
           curves; "Hollywood seems full of curvaceous blondes"; "a
           curvy young woman in a tight dress" [syn: bosomy,
           busty, buxom, curvaceous, curvy, full-bosomed,
           sonsie, sonsy, stacked, voluptuous, well-
           endowed]
    2: (of a female body) healthily plump and vigorous ; "a
       generation ago...buxom actresses were popular"-
       Robt.A.Hamilton; [syn: buxom, zaftig, zoftig]

Moby Thesaurus II by Grady Ward, 1.0:

104 Moby Thesaurus words for "buxom":
   Junoesque, adipose, agreeable, amply endowed, attractive, becoming,
   beefy, big-bellied, bloated, blowzy, bonny, bosomy, braw, brawny,
   built, built for comfort, burly, busty, callipygian, callipygous,
   chesty, chubby, chunky, comely, corpulent, curvaceous, curvy,
   distended, dumpy, fair, fat, fattish, fleshy, frivolous, full,
   gleeful, goddess-like, gross, healthy, hearty, heavyset, hefty,
   hilarious, hippy, imposing, jocular, jocund, jolly, jovial, joyful,
   joyous, laughter-loving, likely, lovely to behold, lusty, meaty,
   merry, mirth-loving, mirthful, obese, overweight, paunchy,
   personable, pleasing, plump, pneumatic, podgy, portly, potbellied,
   presentable, pudgy, puffy, pursy, rejoicing, risible, roly-poly,
   rotund, shapely, sightly, slender, square, squat, squatty, stacked,
   stalwart, statuesque, stocky, stout, strapping, swollen,
   thick-bodied, thickset, top-heavy, tubby, vigorous, well-built,
   well-developed, well-favored, well-fed, well-formed, well-made,
   well-proportioned, well-shaped, well-stacked