I wanted to thoroughly investigate the 2 Words, along with 3 other Words, along with Quranic Usage and along with an attempt to find out the core meaning shades from dictionaries and then putting them to the test using The Quran. Maybe, no viewer of my blogs wants such a thorough research? Perhaps they want it but not from me, but the ones you prefer apparently don't prefer such time consuming research. Conventional approach gives the easy option of translating them as heart and move on. A person not afraid of standing alone, not afraid of spending as much time as the research demands, not afraid of presenting findings different from the majority view, can attempt such research.
Below is a draft version of only 1 step of the research:
قَلۡب فُؤَاد