Tantra तन्त्र , "loom, warp"; hence "principle, system, doctrine", from the two root words tanoti "stretch, extend, expand", and trayati "liberation"
. . . Tantra in the Buddhist context is totally different from Hindu. The entire culture is different. The meaning of the word is different - based on two different etymologies of the Sanskrit language. In Buddhism, it means continuum, which is related to Chitta-Santaan (mental continuum), whereas in Hinduism, it means liberating the finite consciousness by merging it into the Infinite. Since there is no such Infinite in Buddhism into which the finite consciousness can merge and there is not ultimately real finite consciousness, it cannot merge into an Infinite. The whole Hindu context found in Hindu Tantra does not apply at all to Buddhist Tantra. In Hinduism, Tantra has earned a bad name but this is not true of Buddhist Tantra within Buddhism. Anyway, the word Tantra does not mean the same thing in the two systems as many uninformed scholars have thought.
-from http://www.byomakusuma.org/Teachings/Va ... syana.aspx