Source : Webster's Revised Unabridged Dictionary (1913)

Urosteon \U*ros"te*on\, n.; pl. L. {Urostea}, E. {Urosteons}.
   [NL., fr. Gr. ? the tail + ? a bone.] (Anat.)
   A median ossification back of the lophosteon in the sternum
   of some birds.