Noun
commonwealthman (plural commonwealthmen)
(historical) Someone who lived under the English Commonwealth of the 17th century, especially an adherent of it; loosely, a republican.
The Eighteenth-Century Commonwealthman: Studies in the Transmission, Development, and Circumstance of English Liberal Thought from the Restoration of Charles II until the War with the Thirteen Colonies (1959, 2004). Source: Internet