The Collaborative International Dictionary of English v.0.48:

Bulbous \Bulb"ous\, a. [L. bulbosus: cf. F. bulbeux. See Bulb,
   n.]
   Having or containing bulbs, or a bulb; growing from bulbs;
   bulblike in shape or structure.
   [1913 Webster]

WordNet (r) 3.0 (2006):

bulbous
    adj 1: shaped like a bulb [syn: bulblike, bulbous, bulb-
           shaped]
    2: curving outward [syn: bellied, bellying, bulbous,
       bulging, bulgy, protuberant]

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "bulbous":
   bagging, baggy, ballooning, bellying, billowing, billowy, bloated,
   bosomy, botanic, bulblike, bulbose, bulging, bumped, bumpy,
   bunched, bunchy, cereal, distended, ellipsoid, farinaceous,
   fruitlike, fruity, global, globate, globe-shaped, globed,
   globelike, globoid, globose, globular, hemispheric, herbaceous,
   herbal, herbose, herbous, herby, hillocky, hummocky, leguminose,
   leguminous, moutonnee, obovoid, orb, orbed, orbic, orbicular,
   orbiculate, orblike, orby, ovoid, plantlike, pneumatic, potbellied,
   pouching, radicated, radiciform, radicular, rhizoid, rootlike,
   rounded, sphere-shaped, spherelike, spheric, spheriform, spheroid,
   swelling, tuberous, vegetable, vegetal, vegetarian, vegetational,
   vegetative, verrucated, verrucose, warty, weedy