The proposed technology relates to an indexable cutting insert (10) for a cutting tool. The cutting insert (10) comprises: a first side surface (12) and an opposing second side surface (14), and a peripheral surface (16) extending between the first side surface (12) and the second side surface (14). The cutting portion (18) comprises a first cutting face (24) and an opposing second cutting face (26), a flank face (28) extending between the first cutting face (24) and the second cutting face (26), a first cutting edge (20) between the first cutting face (24) and the flank face (28), and a second cutting edge (22) between the second cutting face (26) and the flank face (28). The cutting portion (18) is bisected by a first plane (AA′) transverse to the first side surface (12) and the cutting portion (18) has a biconcave cross-section transverse to the first plane (AA′).

A two-way indexable V-shaped cutting insert having first and second rake surfaces located in a front insert surface thereof. First and second relief surfaces respectively connect the first and second rake surfaces to first and second converging insert abutment surfaces, respectively. A first cutting edge is located at an intersection of the first rake surface and the first relief surface. A second cutting edge is located at an intersection of the second rake surface and the second relief surface. A first relief angle is formed between the first relief surface and the first converging insert abutment surface. A second relief angle is formed between the second relief surface and the second converging insert abutment surface. The first and second relief angles are obtuse. In a cutting tool, the two-way indexable V-shaped cutting insert is releasably secured in a tool holder by means of a fastening member.