All-ground

Buddha Nature (bde gshegs snying po):

It is not an "entity" but ultimate nature of mind, free from veils of ignorance. Every sentient being has the potential to actualize this buddha nature by revealing perfect knowingness through pristine cognition of this nature of mind. This is in a way the "primordial goodness" of sentient beings. The innate all-pervasive primordial purity. [MR]

Buddha nature (bde gshegs snying po). Sugata garbha, the essence of the sugatas; the potential for enlightenment or enlightened nature that is inherently present in each sentient being. For a detailed discussions, see Thrangu Rinpoche's 'Buddha Nature,' Rangjung Yeshe Publications. RY