\Pet"al*ism\, n. [Gr. ?, fr. ? a leaf: cf. F.
p['e]talisme.] (Gr. Antiq.)
A form of sentence among the ancient Syracusans by which they
banished for five years a citizen suspected of having
dangerous influence or ambition. It was similar to the
ostracism in Athens; but olive leaves were used instead of
shells for ballots.