1. In Saṃkhya philosophy, in Hinduism, tattvas are the constituent subtle elements of prakṛti; in Jainism, tattva is the categorical (i.e. true) constituent of appearance and release.
2. In Buddhism, tattva does not have the same technical philosophical sense. The proto-Mahāyānist Prajñaptivādins defined tattva as the real phenomenon which underlies concept (prajñapti). In the Vijñanāvāda (Yogācāra) this meaning is substantially retained, though now extended to take in the totality of entities. The Ratnagotravibhāga of Asaṅga talks of reality (tattva) being devoid of the subject-object dichotomy, and other texts by the same author state that, since words and concepts do not partake of the nature of the things they denote, tattva is ultimately inexpressible.
Authors representing the Mādhyamaka tendency are careful not to use tattva in the Yogācārin sense in their effort to avoid all terms which may be taken as absolutes. Nāgārjuna does, however, talk of the reality or truth (tattva) of the Buddha's teaching.
"Tattva." The Concise Oxford Dictionary of World Religions. . Encyclopedia.com. (September 22, 2018). http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/tattva
"Tattva." The Concise Oxford Dictionary of World Religions. . Retrieved September 22, 2018 from Encyclopedia.com: http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/tattva