Broken pieces of pottery that was then used as writing material. The plural is ostraca.
An ostracon may be inscribed with a sharp instrument or the writings may be done in ink. Ostraca are an important source of information for archaeologists as they were often used for short letters, receipts, inventory tabs, as well as abecedaries (for practicing to write).
In ancient Greece a person may be banished from society by a vote of the people written on broken pieces of pottery or tile. From this practice is derived the English verb, ostracize, meaning to banish or exclude from society.
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