biconvex, convexo-convex, lenticular, lentiform

from The Collaborative International Dictionary of English v.0.48

bulging \bulging\ adj.
   1. curving or bulging outward. Opposite of {concave}.
      [Narrower terms: {biconvex, convexo-convex, lenticular,
      lentiform}; {broken-backed, hogged}; {convexo-concave};
      {gibbous, gibbose}; {planoconvex}] Also See: {protrusive}.

   Syn: convex.
        [WordNet 1.5]

   2. curving outward.

   Syn: bellied, bellying, bulbous, bulgy, protuberant.
        [WordNet 1.5]