Peer of the Realm is a term for a member of the (aristocratic) highest social order (not considering the ruling dynasty) in a kingdom, notably:
a member of the peerage in the British Isles who is a hereditary peer or a life peer
the English rendering of a member of a similar order in other monarchies, derived from the French noble style of pair as used in
the French kingdom
the crusader state kingdom of Jerusalem
nobility proper of the Polish-Lithuanian Commonwealth who enjoyed hereditary paritas: those who would sit by hereditary right in Land Parliaments, or be Royal Electors, enjoy personal immunity, and the right to be judged only by the King's Court or the Court of Peers; also the exclusive right to be granted State or Land dignities and titles. The Skartabelli who were middle-nobility in law were not peers, whilst noblemen who were not direct barons of the Crown but held land from other Lords were not peers de facto as they would not enjoy full noble privileges.
a member of the Portuguese Chamber of Most Worthy Peers, upper house of the Cortes Gerais, during the constitutional monarchy of the Kingdom of Portugal
