The word tantra is derived from the combination of two words 'tattva' and 'mantra'. Tattvameans the science of cosmic principles, while mantra refers to the science of mystic sound and vibrations. Tantra, therefore, is the application of cosmic sciences with a view to attain spiritual ascendancy. In another sense, tantra also means the scripture by which the light of knowledge is spread: Tanyatevistaryatejnanamanemnaititantram.
There are essentially two schools of Indian scriptures - Agama and Nigama. Agamas are those which are revelations while Nigama are the traditions. Tantra is an Agama and hence it is called srutishakhavisesah, which means it is a branch of the Vedas.
The Sanskrit word tantra means the warp of a loom or the strands of a braid. Like the strings of a warp, the tantra practices serve as a structure for intertwining the sutra themes to weave a tapestry of enlightenment. Moreover, it combines physical, verbal, and mental expressions of each practice, which braid together creating a holistic path of development. Because one cannot integrate and practice simultaneously all the sutra themes without previously training in each individually, tantra practice is extremely advanced.
The root of the word tantra means to stretch or to continue without a break. Tantramolds the power of creation and ego into skillful means cutting through delusion, requires careful preparation. It is a path of tremendous power.
Tantra (a Sanskrit word which means "woven together") is a term loosely applied to several divergent and even contradictory schools of Hindu yoga in which the union of male and female is worshipped either in principle or in human practice. It has also come to be applied to sex-based religious practices developed in some religious cults.