Definition
An imaginary straight line drawn from the leading edge of an airfoil to the trailing edge. The chord is used as the reference line for measuring angle of attack and for describing the shape and dimensions of a wing.
Plain English
A straight line running from the front edge of the wing to the back edge. It's the reference line used to describe how the wing is shaped and how it's tilted into the oncoming air.
Context Anchor
Seen in angle of attack discussions, where the wing’s chord line is compared with the oncoming airflow.
Derivation
From the Latin chorda, meaning 'string' or 'cord.' In geometry, a chord is a straight line connecting two points on a curve. A wing, viewed from the side, is a curved shape — and the chord is the straight line cutting across it from leading edge to trailing edge.
Why Pilots Care
The chord line is the reference used to measure angle of attack and to understand how wing shape produces lift.
Intuition Check
Chord does not mean a musical note here. In this context, it means the straight reference line from the front of a wing shape to the back.
Example Sentence 1
Angle of attack is the angle between the chord line of the wing and the relative wind.
Example Sentence 2
A longer chord increases the wing area and therefore changes the amount of lift produced at a given speed.