From Lappa- + -i (compare lappalainen). There are two main theories on the origin of this word:[1]
Swedishlapp(“patch”), as a calque of a Sami endonym vuowjoš (seemingly derived from the same word whence also Lule Samivuojvve(“patch (of textile), gusset”))
related to lape, (dialectal) lappea, originally in the meaning "remote place" (compare Mokshaлапш(lapš), Erzyaлапужа(lapuža, “flat”))
Lappi is the 654th most common surname in Finland, belonging to 1,317 individuals, according to February 2023 data from the Digital and Population Data Services Agency of Finland.