From 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.