Buddhadhātu

buddhadhātu (T. sangs rgyas kyi khams སངས་རྒྱས་ཀྱི་ཁམས་; C. foxing 佛性) refers to the inherent potential of all sentient beings to achieve buddhahood.

The Tsadra Foundation "Buddha-nature" website states:

[Buddhadhātu is] a synonym for tathāgatagarbha widely used throughout the East Asian Buddhist traditions, as found in its translations as the Chinese term foxing and Japanese term busshō.

This is most likely the direct source of the English term buddha-nature via its translation into Chinese and Japanese. These traditions tended to treat the Sanskrit terms dhātu, gotra, and garbha as synonyms when compounded with the term buddha, though the translation of buddhadhātu seems to have been adopted as the standard technical term to reference the buddha-nature doctrine, as it could cover a wider range of possible meanings. In other words, the term dhātu could more easily reference both the causal aspect of this nature, commonly associated with the term gotra, and the fruition aspect of this nature, commonly associated with the term garbha.