The Collaborative International Dictionary of English v.0.48:

oo \o"o\, n. [Hawaiian.] (Zool.)
   Any of several beautiful birds of the genus Moho, including
   the extinct Moho nobilis. They are honey-eaters native to
   the Hawaiian Islands. It yields the brilliant yellow feathers
   formerly used in making the royal robes. Called also
   yellow-tufted honeysucker.
   [1913 Webster]