Dharmakāya

The dharmakāya (Sanskrit: धर्मकाय; Pali: धम्मकाय, lit. "truth body" or "reality body") is one of the three bodies (trikaya) of the Buddha in Mahayana Buddhism. Dharmakāya constitutes the unmanifested, "inconceivable" (acintya) aspect of a Buddha, out of which Buddhas arise and to which they return after their dissolution. Buddhas are manifestations of the dharmakāya called nirmanakaya ("transformation body"). Reginald Ray writes of it as "the body of reality itself, without specific, delimited form, wherein the Buddha is identified with the spiritually charged nature of everything that is."

The Dhammakaya Movement of Thailand and the Tathāgatagarbha sūtras of the ancient Indian tradition view the Dharmakāya as the true self of the Buddha, present within all beings.

In Tibetan, the term chos sku glosses Dharmakāya; it is composed of chos "religion, dharma" and sku "body, form, image, bodily form, figure". Thondup & Talbott render it as the "ultimate body". In a key scholarly collaborative, Nyingma translation work published in 2005, furthermore notable as the first complete rendering of the Bardo Thodol into the English language from the Tibetan, this technical term was configured into English as "Buddha-body of Reality".

The Yungdrung Bon term for dharmakāya is rdzogs sku, where rdzogs means "perfection".

In the Pāli Canon, Gautama Buddha tells Vasettha that the Tathāgata (the Buddha) is Dhammakaya, the "Truth-body" or the "Embodiment of Truth", as well as Dharmabhuta, "Truth-become", that is, "One who has become Truth."

He whose faith in the Tathagata is settled, rooted, established, solid, unshakeable by any ascetic or Brahmin, any deva or mara or Brahma or anyone in the world, can truly say: 'I am a true son of Blessed Lord (Bhagavan), born of his mouth, born of Dhamma, created by Dhamma, an heir of Dhamma.' Why is that? Because, Vasettha, this designates the Tathagata: 'The Body of Dhamma,' that is, 'The Body of Brahma,' or 'Become Dhamma,' that is, 'Become Brahma.'"

...
Wikipedia