A right-angled joint is a type of mechanical connection that forms a 90-degree angle between two pieces of material. It is commonly used in carpentry and construction to join two pieces of wood, metal, or other materials together. The term 'right-angled joint' can also refer to the ELL, which is a three-letter abbreviation for an elbow joint. An elbow joint is a type of right-angled joint that is used to connect two pipes at a 90-degree angle.