gateway drug

1. 入门毒品，诱导性毒品（如大麻，一些人认为此类毒品可诱人吸食更为有害的毒品）
   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.

1. Marijuana does not appear to be a gateway drug to the extent that it is the cause or even that it is the most significant predictor of serious drug abuse, the Institute of Medicine study said.
   药学研究中心的报告说，大麻并不是一种入门药物，并不是药物严重滥用的原因，甚至也不是药物严重滥用的重要预示因素。

noun

1. a habit-forming drug that is not addictive but its use may lead to the use of other addictive drugs
   1. one college athlete recently called beer a gateway drug for young people