The Taittirīya Upanishad (Devanagari: तैत्तिरीय उपनिषद्) is a Vedic era Sanskrit text, embedded as three chapters (adhyāya) of the Yajurveda. It is a mukhya (primary, principal) Upanishad, and likely composed about 6th century BC .
The Taittirīya Upanishad is associated with the Taittirīya school of the Yajurveda, attributed to the pupils of sage Tittiri (literally, "Partridge"). It lists as number 7 in the Muktika canon of 108 Upanishads.
The Taittirīya Upanishad is the seventh, eighth and ninth chapters of Taittirīya Āraṇyaka, which are also called, respectively, the Śikṣāvallī, the Ānandavallī and the Bhṛguvallī. This Upanishad is classified as part of the "black" Yajurveda, with the term "black" implying "the un-arranged, motley collection" of verses in Yajurveda, in contrast to the "white" (well arranged) Yajurveda where Brihadaranyaka Upanishad and Isha Upanishad are embedded.
The Upanishad includes verses that are partly prayers and benedictions, partly instruction on phonetics and praxis, partly advice on ethics and morals given to graduating students from ancient Vedic gurukula-s (schools), partly a treatise on allegory, and partly philosophical instruction.
Taittiriya is a Sanskrit word that means "from Tittiri". The root of this name has been interpreted in two ways: "from Vedic sage Tittiri", who was the student of Yāska; or alternatively, it being a collection of verses from mythical students who became "partridges" (birds) in order to gain knowledge. The later root of the title comes from the nature of Taittriya Upanishad which, like the rest of "dark or black Yajur Veda", is a motley, confusing collection of unrelated but individually meaningful verses.
Each chapter of the Taittiriya Upanishad is called a Valli (वल्ली), which literally means a medicinal vine-like climbing plant that grows independently yet is attached to a main tree. Paul Deussen states that this symbolic terminology is apt and likely reflects the root and nature of the Taittiriya Upanishad, which too is largely independent of the liturgical Yajur Veda, and is attached to the main text.