from the GNU version of the Collaborative International Dictionary of English
- n. 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.
from The Century Dictionary and Cyclopedia
- n. In ancient Syracuse, a mode of banishing citizens whose influence seemed dangerous, modeled on the ostracism at Athens, from which it differed in little except that the voter wrote the name of the person he recommended for banishment on an olive-leaf and not on a tablet of earthenware, and that the stated period of banishment was five years, and not ten as at Athens.
From Middle French petalisme, and its source, Hellenistic Ancient Greek πεταλισμός, from πέταλον ("leaf") (because the ballot for banishment was written on olive leaves). (Wiktionary)