Emily Dickinson Lexicon

FEN, n. [Sax. fen or fenn; D. veen; Arm. fenna, to overflow; W. fynu, to abound, to produce; hence L. fons, Eng. fountain.]

Low land overflowed, or covered wholly or partially with water, but producing sedge, coarse grasses, or other aquatic plants; boggy land; a moor or marsh. A long canal the muddy fen divides.