Psilocybe is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of small mushrooms growing worldwide. This genus is best known for its species with psychedelic or hallucinogenic

Psychedelic drug

A psychedelic substance is a psychoactive drug whose primary action is to alter cognition and perception. Psychedelics are part of a wider class of psychoactive drugs known as hallucinogens, a class that also includes related substances such as dissociatives and deliriants...

 properties, widely known as "magic mushrooms

Psychedelic mushroom

Psilocybin mushrooms are fungi that contain the psychoactive compounds psilocybin and psilocin. There are multiple colloquial terms for psilocybin mushrooms, the most common being shrooms or magic mushrooms....

", though the majority of species do not contain hallucinogenic compounds. Psilocin

Psilocin

Psilocin , an aromatic compound, sometimes also spelled psilocine, psilocyn, or psilotsin, is a psychedelic mushroom alkaloid. It is found in most psychedelic mushrooms together with its phosphorylated counterpart psilocybin...

 and psilocybin

Psilocybin

Psilocybin is a naturally occurring psychedelic prodrug, with mind-altering effects similar to those of LSD and mescaline, after it is converted to psilocin. The effects can include altered thinking processes, perceptual distortions, an altered sense of time, and spiritual experiences, as well as...

 are the hallucinogenic compounds responsible for the psychoactive effects of many species in the genus.

The word Psilocybe comes from the Greek

Ancient Greek

Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...

 words ψιλός + κύβη, and literally means "bare headed", referring to the mushroom's detachable pellicle (loose skin over the cap).