Pronunciation: (ō'ō),[key] —n., —pl.o-os. any of several species of Hawaiian honey eaters of the genus Moho, esp. the extinct M. nobilis, of the island of Hawaii, that had black plumage and two tufts of yellow plumes used to make ceremonial robes for the Hawaiian kings. Also,o'o,o''o.
a combining form meaning “egg,” used in the formation of compound words: oogamous.