Merriam-Webster Collegiate Dictionary - rhea

 noun  Etymology: New Latin, genus of birds, probably from Latin Rhea, mother of Zeus, from Greek  Date: 1797 either of two South American ratite birds (Rhea americana and Pterocnemia pennata of the family Rheidae) that resemble but are smaller than the African ostrich and that have three toes, a fully feathered head and neck, an undeveloped tail, and pale gray to brownish feathers that droop over the rump and back