Anti/ˈæntaɪ/ Definition 1 of 5Pro Tip 1/3Common Associations Often used with words related to conflict, defense, or prevention. The antiwar activist organized a rally. Pro Tip 2/3Emotional Charge Can imply a strong stance or evoke emotions when combined with certain topics. Her antigovernment speech stirred the crowd. Pro Tip 3/3Preventive Nuance Used to describe substances or actions designed to prevent undesirable conditions. She added antifreeze to her car's radiator.