Definition of Piast in US English:

Piast

noun

History
  • A member of the first Polish royal dynasty; a person descended from this dynasty. Also more generally: any Polish-born candidate at a royal election.

Origin

Mid 17th century; earliest use found in James Howell (?1594–1666), historian and political writer. From Piast (also as Piastus, Pyast, Pyastus), the name of the legendary founder of the first Polish royal dynasty (850) and subsequently denoting a member of this dynasty. In plural forms denoting the dynasty itself.