Frithville is both a parish and a village which lie in the Fens about 5 miles north of Boston. The parish covers about 4,200 acres and includes the former parish (or extra-parocial land) of Westville, which is 7 miles north of Boston. It also includes the village of Mount Pleasant.
The name derives from the Old English Fyrhth, meaning "sparse woodland", with the French "ville" added at a later date. It appears in 1331 as Le Frith. A. D. Mills, "A Dictionary of English Place-Names," Oxford University Press, 1991.
The village and parish are sometimes called Boston East.