The term "2π radians" refers to a complete rotation around a circle. In the context of angles, a full circle measures 360 degrees, which is equivalent to 2π radians. This means that when you rotate an object or point all the way around, it has traveled an angle of 2π radians. Radians are a unit of angular measurement used in mathematics and physics. They are based on the radius of a circle, where one radian is the angle formed when the arc length is equal to the radius. Thus, 2π radians is a fundamental concept in trigonometry and is essential for understanding circular motion and periodic functions.