(of a bird) having a flat breastbone without a keel, and so unable to fly (鸟)平胸的;有平胸的。 与 carinate 相对
noun
any of the mostly large, flightless birds with such a breastbone, i.e. the ostrich, rhea, emu, cassowary, and kiwi, together with the extinct moa and elephant bird 平胸鸟