To design γ-γ´ strengthened medium entropy alloys (MEAs) with a γ´ volume fraction exceeding 40 % with an excellent combination of room and elevated temperature mechanical properties, remains a major challenge for material scientists. In this work, we report a novel γ-γ´ strengthened Ni-Co-Cr-Al-Ti based medium entropy superalloy (MESA) with low density 7.84 gcm-3, designed based on CALPHAD approach for turbine disc applications. In the as-cast stage, coarsened γ´ precipitates and irregular eutectic (γ+γ´) phases were found in interdendritic region, whereas fine γ´ precipitates are uniformly distributed in the dendritic region. Excellent tensile properties were achieved with yield strength of 833 MPa, ultimate tensile strength of 1080 MPa and ductility of 22 % in the as-cast condition. Solid solution strengthening and precipitation strengthening are the main strengthening mechanisms. The low density and high specific yield strength (106.3 MPa.g-1cm-3) makes this alloy a potential alternative to Waspaloy and other Ni-based superalloys for turbine disc applications.