O7 is a common military chat term that is used to acknowledge a soldier (usually general) who has just spoken. It is usually used by soldiers in the field of combat and is frequently used to acknowledge a superior who has just given a command. For example, if a soldier has to pass a message, they would say ‘o7’ to acknowledge that they have understood the order and are moving to carry it out. On Snapchat, WhatsApp, Facebook, Twitter, and Instagram, O7’s definition is “I Salute You.”