(I can't be certain that playing Lumosity is helping to keep my brain active - I think it is - but it's definitely giving me words to blog about, so that's a win for me.)
The online Oxford Dictionary says:
NounWhich, of course, left me thinking, 'Wow! Those ancient Greeks didn't know the difference between a sparrow and an ostrich?'
1 a flightless swift-running African bird with a long neck, long legs, and two toes on each foot . It is the largest living bird, with males reaching a height of up to 2.75 m.
* Struthio camelus, the only member of the family Struthionidae
2 a person who refuses to face reality or accept facts:don’t be an ostrich when it comes to security systems[from the popular belief that ostriches bury their heads in the sand if pursued]
Middle English: from Old French ostriche, from Latin avis 'bird' + late Latin struthio (from Greek strouthiōn 'ostrich', from strouthos 'sparrow or ostrich')
An entry in freefictionbooks.org makes the interesting point that the word thus has its origins in both Greek and Latin.
The name "ostrich" has an interesting history. The Greeks called this singular bird _struthion'_. This came into the Latin language as _struthio_. In low Latin, _avis_, the Latin word for "bird," was prefixed to what remained of the Greek name, giving _avis struthio_. "Ostrich" is a contraction of this low Latin compound. So we have in this name a combination of two words from different languages, having the same meaning.And I guess those Greeks could see the difference between a sparrow and an ostrich, by the way - they called it either 'big sparrow' or 'camel sparrow'. Online Etymology dictionary says:
early 13c., from O.Fr. ostruce (Fr. autruche), from V.L. avis struthio, from L. avis "bird" (from PIE *awi- "bird") + L.L. struthio "ostrich," from Gk. strouthion "ostrich," from strouthos melage "big sparrow." The Greeks also knew the bird as strouthokamelos "camel-sparrow," for its long neck. Among its proverbial peculiarities are indiscriminate voracity (especially a habit of swallowing iron and stone to aid digestion), want of regard for its eggs, and a tendency to hide its head in the sand when pursued.
Like the Austridge, who hiding her little head, supposeth her great body obscured. 
Ostriches do put their heads in the sand, but ostrich farmers say they do this in search of something to eat.
And I've learned a new word in the process - I found struthious [ˈstruːθɪəs] in The Free Dictionary
1. (Life Sciences & Allied Applications / Animals) (of birds) related to or resembling the ostrich
2. (Life Sciences & Allied Applications / Animals) of, relating to, or designating all flightless (ratite) birds
[from Late Latin strūthiō, from Greek strouthiōn, from strouthos an ostrich]
Collins English Dictionary – Complete and Unabridged © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003