The Collaborative International Dictionary of English v.0.48:

Campanula \Cam*pan"u*la\ (k[a^]m*p[a^]n"[-u]*l[.a]), prop. n.
   [LL. campanula a little bell; dim. of campana bell.] (Bot.)
   A large genus of plants bearing bell-shaped flowers, often of
   great beauty; -- also called bellflower.
   [1913 Webster]

WordNet (r) 3.0 (2006):

campanula
    n 1: any of various plants of the genus Campanula having blue or
         white bell-shaped flowers [syn: campanula, bellflower]