A wide-body aircraft is a large airliner with two passenger aisles, also known as a widebody aircraft or twin-aisle aircraft. The typical fuselage diameter is 5 to 6 m (16 to 20 ft). In the typical wide-body economy cabin, passengers are seated seven to ten abreast, allowing a total capacity of 200 to 850 passengers. The largest wide-body aircraft are over 6 m (20 ft) wide, and can accommodate up to eleven passengers abreast in high-density configurations.

By comparison, a traditional narrow-body airliner has a diameter of 3 to 4 m (10 to 13 ft), with a single aisle, and seats between two and six people abreast.

Wide-body aircraft were originally designed for a combination of efficiency and passenger comfort. However, airlines quickly gave in to economic factors, and reduced the extra passenger space in order to maximize revenue and profits.

Wide-body aircraft are also used for the transport of commercial freight and cargo and other special uses, described further below.

The largest wide-body aircraft, such as the Boeing 747 and Airbus A380, are known as jumbo jets due to their very large size.