Psychoactive refers to substances or drugs that affect how our brain works and cause changes in awareness, perception, moods, thoughts, consciousness, behavior, or feelings.
When speaking of psychoactive (or psychotropic) substances, we refer not only to things like nicotine, caffeine, alcohol, or marijuana but also to specific pain-reducing medicines.
Illegal drugs and substances such as cocaine, heroin, amphetamines, and LSD also fall in the category of psychoactive substances.
So psychoactive drugs are substances that affect our mental processes when we take them into our system. They influence or affect our cognition.
Psychoactive substances do not necessarily imply that they are dependency-related, but usually, the term is related to substance abuse or drug use.