WordNet sense 1 (tropical American evergreen that produces large round gourds):

calabash tree, Crescentia cujete

WordNet sense 2 (Old World climbing plant with hard-shelled bottle-shaped gourds as fruits):

bottle gourd, Lagenaria siceraria

WordNet sense 3 (bottle made from the dried shell of a bottle gourd):

gourd

WordNet sense 4 (a pipe for smoking; has a curved stem and a large bowl made from a calabash gourd):

calabash pipe