Phencyclidine (a contraction of the chemical name phenylcyclohexylpiperidine; also called PCP, sherm, angel dust, "Wet" or Ashy Larry) is a dissociative psychedelic drug formerly used as an anaesthetic agent.  PCP was commercially developed in the 1950s by the Parke-Davis pharmaceutical company. Internationally, PCP is a Schedule II drug under the Convention on Psychotropic Substances.

PCP was first tested after World War I as a surgical anaesthetic. Because of its bad side-effects, however, it was shelved until the 1950s. It was then patented by Parke-Davis and named Sernyl (supposedly referring to serenity), but was again withdrawn from the market because of side effects. It was soon renamed Sernylan, and marketed as a veterinary anaesthetic, but again discontinued. Its side effects and long half-life in the human body made it unsuitable for medical applications. It is retained in fatty tissue and is broken down by the human metabolism into PCHP, PPC and PCAA. When smoked, some of it is broken down by heat into 1-phenyl-1-cyclohexene (PC) and piperidine.

PCP is sometimes consumed recreationally, mainly in the United States. The limited demand is met by illegal production. The drug is sold in an extremely limited number of cities. It is available as a liquid (PCP base dissolved most often in ether), but typically it is sprayed onto leafy material such as marijuana, mint, oregano, or parsley, and smoked.  In smoking form, embalming fluid is sometimes used to refer to a joint or cigarette dipped in embalming fluid, although it is difficult to determine how frequent this practice is because "embalming fluid" is, itself, a slang term for PCP.In its powder form, PCP can be snorted. This method is popular in Quebec but apparently not in the United States.  In its pure form, PCP is a white crystalline powder that readily dissolves in water. However, most PCP on the illicit market contains a number of contaminants as a result of makeshift manufacturing, causing the color to range from tan to brown, and the consistency to range from powder to a gummy mass.