Preventive measures are actions taken to avoid or reduce the risk of a potential problem. DEFENSIVE measures are strategies used to protect against an attack or other danger, such as fortifying a building or using protective gear. An ANTIDOTE is a substance that counteracts a form of poisoning. HYGIENE is the practice of keeping oneself and one's environment clean in order to prevent illness and disease. CONTRACEPTIVE measures are methods used to prevent pregnancy. All of these terms are related to preventive measures, which are taken to reduce the risk of potential problems.