The word tantra, states Patanjali, means "principal, main".
He uses the same example of svatantra as a composite word of "sva" (self) and tantra, then stating "svatantra" means "one who is self-dependent, one who is his own master, the principal thing for whom is himself", thereby interpreting the definition of tantra.
The challenge of defining Tantra is compounded by the fact that it has been a historically significant part of major Indian religions, including Buddhism, Hinduism and Jainism, both in and outside South Asia and East Asia.
When an action or a thing, once complete, becomes beneficial in several matters to one person, or to many people, that is known as Tantra. In contrast, that which benefits by its repetition is called Āvāpa, such as massaging with oil.