A generic term for substances that modify normal behaviour. Examples can be found in the 1971 UN Convention on Psychotropic Substances. Many are subclassified as stimulants or hallucinogens, but the term can also include sedatives, tranquillisers and hypnotics. Psychotropic drugs are differentiated from narcotics, which are more correctly known as narcotic analgesics.

From WHO Lexicon of alcohol and drug terms

Psychotropic:
In its most general sense, a term with the same meaning as "psychoactive'', i.e. affecting the mind or mental processes. Strictly speaking, a psychotropic drug is any chemical agent whose primary or significant effects are on the central nervous system. Some writers apply the term to drugs whose primary use is in the treatment of mental disorders—anxiolytic sedatives, antidepressants, antimanic agents, and neuroleptics. Others use the term to refer to substances with a high abuse liability because of their effects on mood, consciousness, or both—stimulants, hallucinogens, opioids, sedatives/hypnotics (including alcohol), etc. In the context of international drug control, "psychotropic substances" refers to substances controlled by the 1971 Convention on Psychotropic Substances (see conventions, international drug).