 All spellings of the name until the seventeenth century are with "-d-", starting with "Sidulfes mere" circa 1100.The purported 1272 spelling "Sykolvesmere", in W. Rye, "A Calendar of the Feet of Fines for Suffolk" (1900) is an error by Rye; the manuscript of the fine in the National Archives actually has "Sydolvesm[er]e".The village is named after a mere or lake that used to be present near the River Lark, and the first element is the Old English personal name "*Siduwulf", not a Norse name (Keith Briggs and Kelly Kilpatrick, A dictionary of Suffolk place-names, Nottingham