A psychoactive drug is a substance that alters the mind, mood, or behavior of a person. There are a number of synonyms for the term psychoactive drug such as psychotropic, mind-altering, behavior-altering, and mood-altering substances. These drugs are often classified as depressants, stimulants, or hallucinogens depending on their mode of action on the central nervous system. Other synonyms include pharmacologically active substances, psychoactive agents, and psychotomimetic agents. These different terms are often used interchangeably and refer to the same group of substances that have the ability to change a person's mental state or behavior. It is important to note that these drugs can have both positive and negative effects on the user, and should always be used responsibly.