1738, so called because discovered by English anatomist William Cowper (1666-1709); for the surname see Cooper.
the surname (also Munroe, etc.) is said to be ultimately from the River Roe in Derry, Ireland. James Monroe (1758-1831), the fifth U.S. president, was in office from 1817 to 1825. The Monroe Doctrine (so called from 1848) is a reference to the principles of policy contained in his message to Congress on Dec. 2, 1823. Monrovia, the capital of Liberia, also was named for him at its founding in 1822 by the American Colonization Society.
In terms of national psychology, the Monroe Doctrine marked the moment when Americans no longer faced eastward across the Atlantic and turned to face westward across the continent. [Daniel Walker Howe, "What Hath God Wrought"]
c. 1300, Prestre Johan, legendary medieval Christian king and priest, said to have ruled either in the Far East or Ethiopia. Prestre (attested as a surname late 12c.) is from Vulgar Latin *prester, a transition between Latin presbyter and English priest. First mentioned in the West by mid-12c. chronicler Otto of Freising, who told how Johannes Presbyter won a great victory over the Persians and the Medes. Between 1165 and 1177 a forged letter purporting to be from him circulated in Europe. All this recalls the time when the Christian West was militarily threatened on its frontiers by Muslim powers, dreaming of a mythical deliverer. Compare Old French prestre Jehan (13c.), Italian prete Gianni.