“Ultima ratio” is a Latin phrase which means “last resort” or “final argument”. It is used to describe a situation where all other options or means have been exhausted, and only one final course of action remains. This term is often used in contexts such as politics, law, and military strategy to indicate a decisive action taken when all other avenues have failed or are deemed insufficient. The phrase emphasizes the gravity and seriousness of the action being considered or undertaken.