The term 'AGAINST THE OPPOSITION' can be abbreviated to the three-letter acronym 'ATO'. This acronym is used to refer to a situation in which one party is actively working against another party, usually in a competitive or adversarial context. It is often used in sports, politics, and other areas of life where two sides are in opposition to each other. ATO can also be used to describe a situation in which one person or group is actively working to oppose another person or group.