Dhātu (T. khams ཁམས་; C. jie; J. kai; K. kye 界) is a Sanskrit and Pali term that is used in different contexts and takes on different meanings dependending upon the context. Therefore dhātu has multiple translations into the Enlish language.
The term is used in the following contexts:
- aṣṭadaśadhātu (the eighteen dhatus, aka "eighteen elements")
- eye dhatu
- ear dhatu
- mahābhūta (the primary elements)
- Three realms of existence (Skt. trilokadhātu, tridhātu, etc.)
- dharmadhatu - a synonym for the ultimate truth
- An elemental physical substance (i.e. the physical remains of a body)
- As a synonym for "gotra" within the Ratnagotravibhaga
Contemporary translator David Karma Choephel states:
The word khams or dhatu is used in different contexts that must be translated differently in English. The Sanskrit dhatu is derived from a verb meaning to hold. Mikyo Dorje described its etymology as: "Since it grasps the form of the result or holds its characteristics, it is called element." [khams ni dha tu zhes pa dh'a ra'i sgra las 'bras bu'i gzugs len pa'am rang gi mtshan nyid 'dzin pas khams so//] The word also has a meaning of family or caste, as in the potential. The eye and so forth are presented as elements because they are able to produce future instances of their own same family.
In the presentation of the eighteen elements--the six outer elements of form, etc., the six inner of eye, etc., and the six consciousnesses--they are called elements to emphasize that these are the constituents that produce future consciousnesses. This is in contrast to the twelve sense bases (skye mched), where the same dharmas are referred to in a way that stresses the constituents that support the present consciousness.
In the context of the Desire Realm, Form Realm, and Formless Realm, khams is translated as realm. This is of course idiomatic English, but translators must take care to differentiate this from the six classes of sentient beings that are sometimes called the "six realms."
In the Sanskrit word "dharmadhatu," a synonym for the ultimate truth, the word dhatu contains the meaning of cause, according to Maitreya in Distinguishing the Center and Edges. In this instance it was translated into Tibetan not as khams but as dbyings, or expanse. It seems appropriate to follow the Tibetan translators' example in English and translate that term as "dharma expanse."
- Robert E. Buswell Jr., Donald S. Lopez Jr., The Princeton Dictionary of Buddhism (Princeton: 2014), s.v. dhātu