The Collaborative International Dictionary of English v.0.48:
Ostracize \Os"tra*cize\, v. t. [imp. & p. p. Ostracized; p.
pr. & vb. n. Ostracizing.] [Gr. 'ostraki`zein, fr.
'o`strakon a tile, a tablet used in voting, a shell; cf.
'o`streon oyster, 'oste`on bone. Cf. Osseous, Oyster.]
1. (Gr. Antiq.) To exile by ostracism; to banish by a popular
vote, as at Athens. --Grote.
2. To banish from society, by a general consent; to exclude
from social, political, or private favor; to exclude from
conversation or friendship; to shun; as, he was ostracized
by his former friends. A person may be ostracized by a
formal vote or by a widespread but informal agreement.
[1913 Webster +PJC]