Norse placename element, particularly in the East Midlands, and also in Cumbria, which indicates that in the 9c and 10c Danish Vikings settled there in numbers enough to name the place, often after a person. Thus Grimsby,
Thoresby, Salmonby in the east; also Kirkby in the north and north-west. [OldEngl. by = farmstead, settlement]
Cf. -ing
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.