A cutting tool comprising a tool body having a first insert receiving pocket and an indexable cutting insert removably mounted therein: the first insert receiving pocket comprising a first seat surface and a first support wall transverse thereto; and the cutting insert comprising opposing upper and lower surfaces (36, 38) and a continuous boundary surface extending therebetween, the boundary surface having a plurality of N1 first peripheral surfaces (48a, 48b) circumferentially alternating with a plurality of N1 second peripheral surfaces (50a, 50b), N1 being a whole number greater than one, each first peripheral surface (48a, 48b) intersecting the upper surface to form a first upper cutting edge (52a, 52b), and each second peripheral surface (50a, 50b) intersecting the upper surface to form a second upper cutting edge (54a, 54b), wherein the cutting insert is indexable about a first axis passing through the upper and lower surfaces (36, 38), and a median plane perpendicular to the first axis intersects the boundary surface, wherein the cutting insert has N1 index positions with the lower surface in contact with the first seat surface, and in each index position: the first support wall contacts only one of the first peripheral surfaces (48a, 48b) of the boundary surface and prevents translation of the cutting insert in a first direction along the first seat surface, no other portion of the boundary surface being in contact with the first insert receiving pocket, characterised in that the first seat surface has a plurality of male or female first engagement elements (32a, 32b), in that the lower surface has a plurality of discrete, spaced apart female or male lower engaging elements (64a, 64b), and in that the plurality of first engagement elements (32a, 32b) eccentrically contact the plurality of lower engaging elements (64a, 64b) and simultaneously prevent translation of the cutting insert in a second direction perpendicular to the first direction along the first seat surface, the first engagement elements and the lower engaging elements having mutually offset center axes and/or axes of extension. the first insert receiving pocket comprising a first seat surface and a first support wall transverse thereto; and the cutting insert comprising opposing upper and lower surfaces (36, 38) and a continuous boundary surface extending therebetween, the boundary surface having a plurality of N1 first peripheral surfaces (48a, 48b) circumferentially alternating with a plurality of N1 second peripheral surfaces (50a, 50b), N1 being a whole number greater than one, each first peripheral surface (48a, 48b) intersecting the upper surface to form a first upper cutting edge (52a, 52b), and each second peripheral surface (50a, 50b) intersecting the upper surface to form a second upper cutting edge (54a, 54b), each first peripheral surface (48a, 48b) intersecting the upper surface to form a first upper cutting edge (52a, 52b), and each second peripheral surface (50a, 50b) intersecting the upper surface to form a second upper cutting edge (54a, 54b), wherein the cutting insert is indexable about a first axis passing through the upper and lower surfaces (36, 38), and a median plane perpendicular to the first axis intersects the boundary surface, wherein the cutting insert has N1 index positions with the lower surface in contact with the first seat surface, and in each index position: the first support wall contacts only one of the first peripheral surfaces (48a, 48b) of the boundary surface and prevents translation of the cutting insert in a first direction along the first seat surface, no other portion of the boundary surface being in contact with the first insert receiving pocket, characterised in that the first seat surface has a plurality of male or female first engagement elements (32a, 32b), in that the lower surface has a plurality of discrete, spaced apart female or male lower engaging elements (64a, 64b), and in that the plurality of first engagement elements (32a, 32b) eccentrically contact the plurality of lower engaging elements (64a, 64b) and simultaneously prevent translation of the cutting insert in a second direction perpendicular to the first direction along the first seat surface, the first engagement elements and the lower engaging elements having mutually offset center axes and/or axes of extension.