ostracismyoudaoicibaDictYouDict[ostracism 词源字典]
ostracism: [16] In ancient Greece, when it was proposed that a particular person should be sent into exile for a period, because he was becoming a danger to the state, a democratic vote was taken on the matter. The method of registering one’s vote was to inscribe the name of the prospective banishee on a piece of broken pottery. The pieces were counted, and if enough votes were cast against him away he would go for ten years.

The fragment of pottery was called an óstrakon, a word related to Greek ostéon ‘bone’ (source of the English prefix osteo-) and óstreon ‘oyster’ (source of English oyster). To cast such a vote was therefore ostrakízein (whence English ostracize [17]), and the abstract now derived from this was ostrakismós, source of English ostracism.
[ostracism etymology, ostracism origin, 英语词源]
ostracism (n.)youdaoicibaDictYouDict
1580s, a method of 10-year banishment in ancient Athens, by which the citizens gathered and each wrote on a potsherd or tile the name of a man they deemed dangerous to the liberties of the people, and a man whose name turned up often enough was sent away. From Middle French ostracisme (16c.), Modern Latin ostracismus, or directly from Greek ostrakismos, from ostrakizein "to ostracize," from ostrakon "tile, potsherd," from PIE *ost-r-, from root *ost- "bone" (see osseous). The Greek word is related to osteon "bone," ostreion "oyster" (and cognate with German Estrich "pavement," which is from Medieval Latin astracus "pavement," ultimately from Greek ostrakon).

A similar practice in ancient Syracuse (with banishment for five years) was by writing names on olive leaves, and thus was called petalismos.