Chord (aircraft)

In reference to aircraft, chord refers to the distance between the leading edge and trailing edge of a wing, measured in the direction of the normal airflow. These front and back points are referred to as the leading edge and trailing edge.Most wings change their chord over their width (or span). To give a characteristic figure which can be compared among various wing shapes, the mean aerodynamic chord, or MAC, is used. The MAC is somewhat more complex to calculate, because most wings vary in area over the span, growing narrower towards the outer tips. This means that more lift is generated on the wider inner portions, and the MAC moves the point to measure the chord to take this into account. (If a wing was rectangular, rather than tapering or swept, then the chord would simply be the width of the wing in the direction of airflow.)
See more at Wikipedia.org...