Definition
An imaginary straight line drawn from the leading edge to the trailing edge of an airfoil. It is used as a reference line for measuring angle of attack, angle of incidence, and the curvature (camber) of the airfoil.
Plain English
A straight line from the front of the wing to the back, used as the standard reference for measuring the wing's shape and how it meets the oncoming air.
Context Anchor
Seen in aerodynamics, wing shape, performance, and discussions of how a wing meets the oncoming air.
Derivation
Chord comes from the Latin chorda, meaning 'string' or 'cord' — the same idea as a string stretched tight between two points. In geometry, a chord is a straight line connecting two points on a curve. Applied to an airfoil, it's the straight line stretched between the leading and trailing edges of the curved wing shape.
Why Pilots Care
Chord length is used to calculate wing area, aspect ratio, and aerodynamic performance.
Grounding Statement
Picture looking at a wing shape from the side: the chord is the straight line drawn across it from front to back.
Intuition Check
Chord does not mean a musical chord here. It means a straight reference length across the curved shape of an airfoil.
Example Sentence 1
The angle of attack is the angle between the chord line and the relative wind.
Example Sentence 2
Aspect ratio is found by dividing wing span by the average chord of the airfoil.