from The American Heritage® Dictionary of the English Language, 5th Edition

  • noun Government by two joint rulers.

from The Century Dictionary and Cyclopedia

  • noun A government in which the executive power is vested in two persons, as that of the two joint kings of Sparta or of Siam, or as in the case of William and Mary of England.

from the GNU version of the Collaborative International Dictionary of English

  • noun A form of government in which the supreme power is vested in two persons.


  • While the majority of Russians expect Putin to assume the presidency again, political experts say the ruling tandem, which has also become known as a diarchy, will likely continue with the current arrangement of roles.

    The Earth Times Online Newspaper

  • Australia's defence apparatus has a unique "diarchy" structure, whereby the white-collar Defence staff and the uniformed ADF both report directly to the Minster.

    newmatilda.com - Comments

  • Lift the quality of education in secondary schools, better students will fill universities, which will in turn improve inquality and break the Oxford/Cambridge diarchy.

    Education news, comment and analysis | guardian.co.uk

  • We should have no difficulty "were t'other fair charmer away," but with two such candidates, both equally worthy of the honour, we vote for a diarchy instead of a monarchy, and crown them both.

    The plant-lore & garden-craft of Shakespeare


The word 'diarchy' comes from Greek roots meaning 'twice' and 'to rule'.