An indexable end-milling insert including an underside, an upperside and a plurality of cutting edges that are formed between the upperside and a number of clearance sides and that include a chip-removing main edge as well as a surface-wiping wiper edge. The cutting insert has a square basic shape and includes four main edges and four wiper edges that are countersunk to a lower level than the main edges. The wiper edge is included in a lip projecting in relation to a secondary clearance surface and has a tertiary clearance surface, which laterally transforms into a primary clearance surface. The primary clearance surface has a width that decreases from the two opposite ends thereof toward a section having a smallest width therebetween.