Prince
From Tolkien Gateway
Prince was a hereditary title conferred by the kings of Gondor. It was first given by Elendil to a house of Númenorean nobles, to which he was related to, that had settled in Belfalas; in or near to Edhellond. Some two thousand years later, after the drowning of Amroth, Galador was the first of this line to use the title Prince of Dol Amroth.
In T.A. 3019 King Aragorn II of Gondor created the title Prince of Ithilien and gave it to Faramir, the last Ruling Steward.
Peregrin Took was also informally known as the Prince of the Halflings by the people of Minas Tirith during his time there.