PetalismPet"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.