Merriam-Webster Collegiate Dictionary - fen

 geographical name river 300 miles (483 kilometers) N China in central Shanxi flowing SSE into the Huang FEN  I. noun  Etymology: Middle English, from Old English ~n; akin to Old High German ~na ~, Sanskrit pa?ka mud  Date: before 12th century low land that is covered wholly or partly with water unless artificially drained and that usually has peaty alkaline soil and characteristic flora (as of sedges and reeds)  II. noun  (plural ~)  Etymology: Chinese (Beijing) fen  Date: 1916 — see yuan at money table