Coordinates: 52°52′59″N 1°29′13″W / 52.883°N 1.487°W / 52.883; -1.487
Sinfin is a suburb and ward of the city of Derby, in Derbyshire, England. It is situated approximately 3 miles (4.8 km) south-southwest of the city centre on Derby's southern outskirts. The ward, which includes Osmaston as well as Sinfin itself, had a population of 15,128 in 2011. Historically, Sinfin and Osmaston were separate villages before being swallowed up by the expansion of Derby. Osmaston is characterised by inter-war housing developments while much of the housing in Sinfin is postwar. Between the two suburbs lies a more industrialised area dominated by the Rolls-Royce works.
Sinfin is recorded in the Domesday Book produced in 1086 as Sedenfeld as a manor that belonged to baron Henry de Ferrers. Mention is made of two carucates of land assessed to the geld; land for one plough and two villeins having another and of 6 acres (24,000 m2) of meadow. The land was valued at ten shillings. Its undertenant was named William, later William de Rolleston, a vassal to Henry de Ferrers, who displaced a Saxon thegn named Ulfkell. Today the Ferrers name is still seen in Sinfin.