(1):

(pl.) of Struthio

(2):

(n. pl.) A division, or order, of birds, including only the African ostriches.

(3):

(n. pl.) In a wider sense, an extensive group of birds including the ostriches, cassowaries, emus, moas, and allied birds incapable of flight. In this sense it is equivalent to Ratitae, or Dromaeognathae.