a habit-forming drug that is not addictive but its use may lead to the use of other addictive drugs; "one college athlete recently called beer a gateway drug for young people
A gateway drug is a drug such as cannabis that is believed by some people to lead to the use of more harmful drugs such as heroin or cocaine. A habit-forming substance whose use may lead to the abuse of drugs that are more addictive or more dangerous. a drug such as cannabis which is not a very dangerous, but which some people believe leads to the use of more dangerous drugs such as heroin