Pronunciation: (ī'bis),[key] —n., —pl.i•bis•es,(esp. collectively)i•bis. 1. any of several large wading birds of the family Threskiornithidae, of warm temperate and tropical regions, related to the herons and storks, and characterized by a long, thin, downward-curved bill. Cf. sacred ibis. 2. any of certain similar birds belonging to the stork family Ciconiidae, esp. the wood stork, Mycteria americana.