A comic (Adespota fr.33 Kock, 363 K.-A.) allusion to the fact that voting in Athenian ostracisms used pieces of broken pot, ostraka; see omicron 716.
Same entry in Photius kappa585 Theodoridis; more fully, earlier, in Hesychius kappa2266, where however the headword phrase is over-interpreted with an (absurd) assertion that the victims of ostracism were literally whipped and tortured. The citizens of classical Athens enjoyed legal protection from torture under any circumstances; and in ostracism (as opposed to exile: see omicron 717) particular care was taken to preserve the dignity and status of those involved, e.g. by safeguarding their property.