The Collaborative International Dictionary of English v.0.48:

Openbill \O"pen*bill`\, n. (Zool.)
   A bird of the genus Anastomus, allied to the stork; -- so
   called because the two parts of the bill touch only at the
   base and tip. One species inhabits India, another Africa.
   Called also open-beak. See Illust.
   (m), under Beak.
       [1913 Webster]

WordNet (r) 3.0 (2006):

openbill
    n 1: stork with a grooved bill whose upper and lower parts touch
         only at the base and tip