What is the term for the longest side of a right triangle?

The longest side of a right triangle is known as the hypotenuse. This term specifically refers to the side opposite the right angle, and it plays a crucial role in the Pythagorean theorem, which states that in a right triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the lengths of the other two sides. This relationship establishes the hypotenuse as inherently longer than either of the other two sides, which are referred to as the legs of the triangle. Understanding this term is fundamental in geometry, especially when dealing with right triangles, as it also relates to calculations involving triangle properties and trigonometric functions.