Definition of psephism in US English:

psephism

noun

Ancient Greek History
  • A decree enacted by a vote of a public assembly, especially that of ancient Athens.

Origin

Mid 17th century; earliest use found in Thomas Blount (1618–1679), antiquary and lexicographer. From classical Latin psēphisma and its etymon ancient Greek ψήϕισμα psephisma: see -ism.