If something is carcinogenic, it can cause cancer — or, more carefully, it can raise the chance of cancer. Scientists use this word about chemicals, tobacco smoke, some kinds of radiation, and sometimes about a food or a workplace after long study. It is a heavy, formal, medical word: you will meet it on warning labels, in health news, and in science class, not in ordinary chat. Experts like “likely to cause cancer” because one touch does not usually make someone ill; harm, if it comes, often follows a lot of contact over years. In jokes people stretch it (“this job is carcinogenic”) to mean “this is killing me,” but that is not the real meaning. A thing that is carcinogenic is called a carcinogen. Do not mix it with cancerous: cancerous describes tissue that already has cancer; carcinogenic describes something that can cause it.