B2any natural or artificially made chemical that is taken for pleasure, to improve someone's performance of an activity, or because a person cannot stop using it: illegal drugsa drug addictdrug addiction/abuseShe began to suspect that her son was on/taking/doing drugs.She was suspected of being a drug dealer.His son died of a drug overdose.Drugs - general wordsSpecific types of drug›any activity that you cannot stop doing: Work is a drug for him.Passionate or passing interestsAddictionDrug addiction