Definition
The geometric center of a two-dimensional shape or three-dimensional body — the single point that represents the average position of all points in that shape. For a uniform object, the centroid coincides with the center of gravity.
Plain English
The exact middle point of a shape, found by averaging out all of its area or volume. If the shape is made of one even material, this middle point is also where it would balance.
Context Anchor
Seen in weight-and-balance discussions, aircraft design descriptions, and technical explanations of wings, control surfaces, or other shapes.
Derivation
From the Greek 'kentron' meaning 'center,' with the suffix '-oid' meaning 'shaped like' or 'resembling.' So 'centroid' literally means 'center-like point' — the point that represents the center of a shape based purely on its geometry.
Why Pilots Care
Locating the centroid of fuel, cargo, or wing area determines the aircraft center of gravity and affects stability and control margins.
Analogy
Think of a flat cardboard cutout. If the cardboard is the same thickness everywhere, the point where it balances on your finger is its centroid.
Intuition Check
Do not assume centroid always means center of gravity. Centroid is about the center of a shape; center of gravity is about where weight acts.
Example Sentence 1
The centroid of a rectangular wing panel lies at the intersection of its diagonals.
Example Sentence 2
Lift on the tapered wing acts through the centroid of the chordwise pressure distribution.