A rotor for a gas turbine engine is described and includes a disc and a plurality of blades. The disc has opposite first and second end surfaces spaced apart by a peripheral surface circumferentially extending about the rotor, and a plurality of slots defined in the peripheral surface and each having a length extending between a first slot opening in the first end surface and a second slot opening in the second end surface. Each of the slots has a tapered shape with at least one dimension of a cross-sectional shape of the slot reducing along at least a portion of the length of the slot. The at least one dimension at the first slot opening is greater than the at least one dimension at the second slot opening. The blades having a complimentary root are received in the slots of the rotor.