Urceolate

from WordNet (r) 3.0 (2006)

urceolate
    adj 1: urn-shaped; large below and contracted toward the mouth

from The Collaborative International Dictionary of English v.0.48

Urceolate \Ur"ce*o*late\, a. [L. urceolus, dim. of urceus a
   pitcher or waterpot.] (Nat. Hist.)
   Shaped like a pitcher or urn; swelling below, and contracted
   at the orifice, as a calyx or corolla.
   [1913 Webster]