The Collaborative International Dictionary of English v.0.48:

Rotund \Ro*tund"\, n.
   A rotunda. [Obs.] --Burke.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Rotund \Ro*tund"\, a. [L. rotundus. See Round, and cf.
   Rotunda.]
   1. Round; circular; spherical.
      [1913 Webster]

   2. Hence, complete; entire.
      [1913 Webster]

   3. (Bot.) orbicular, or nearly so. --Gray.
      [1913 Webster]

WordNet (r) 3.0 (2006):

rotund
    adj 1: spherical in shape
    2: (of sounds) full and rich; "orotund tones"; "the rotund and
       reverberating phrase"; "pear-shaped vowels" [syn: orotund,
       rotund, round, pear-shaped]
    3: excessively fat; "a weighty man" [syn: corpulent, obese,
       weighty, rotund]

Moby Thesaurus II by Grady Ward, 1.0:

87 Moby Thesaurus words for "rotund":
   adipose, arched, beefy, bellied, bellylike, big-bellied, bloated,
   blowzy, bosomy, bowed, brawny, bulging, burly, buxom, chubby,
   chunky, circular, consonant, convex, convexed, corpulent, crummy,
   deep, distended, dumpy, excurvate, excurvated, excurved, fat,
   fattish, fleshy, full, gibbose, gibbous, globular, gross, heavy,
   heavyset, hefty, hippy, humped, imposing, lusty, meaty, mellow,
   obese, orbicular, orotund, out-bowed, overweight, paunchy,
   plangent, plump, podgy, portly, potbellied, pudgy, puffy, pursy,
   resonant, resounding, reverberant, reverberating, rich, ringing,
   roly-poly, round, rounded, rounded out, sonorous, spherical,
   square, squat, squatty, stalwart, stocky, stout, strapping, stubby,
   swollen, thick, thick-bodied, thickset, top-heavy, tubby, vibrant,
   well-fed