a person inheriting one of the five degrees within the hereditary nobility in Great Britain and Ireland
A hereditary peer may be a duke, marquis, earl, viscount, or baron.
also hereditary peerage , n.
One was plebeian and absolutely poor, the other was a hereditary peer of England and wealthier than many a monarch.
The Government gave up the contest by creating Sir James (who had no son) a hereditary peer.