Psychedelics are a group of substances, plant based and synthetic, that can induce heightened states of consciousness. They include amongst others Psilocybin (mushrooms/truffles), DMT, Ayahuasca,, San Pedro (Huachuma), Peyote, Mescaline and LSD.
The term psychedelic has been commonly used since the 1960s and comes from the Greek psyche, meaning mind or soul and delein meaning to manifest - thus mind/soul manifesting. In the 1950s Aldous Huxley had suggested his own term phanerothyme, coming from Greek phaneroein meaning visible and thymos soul, thus visible soul. For many the term entheogens, generating the divine within is better suited to describe these substances, as this term possibly distinguishes their ancient spiritual role from the recreational uses to which they have often been associated.
Psychedelics or entheogens have been used by many cultures for thousands of years, whether by shamanic practitioners or as part of religious or spiritual practices to reach altered states of consciousness and it has only been in recent times that their power has become known in the West.