Definition
The molecular force of attraction that holds the molecules of a single substance together, giving the substance its internal strength and resistance to being pulled apart.
Plain English
The way the tiny particles inside a material stick to each other, keeping the material in one piece.
Context Anchor
Seen in basic aviation physics, fluid behavior, and weather discussions involving water drops, fuel, oil, or other materials.
Derivation
From the Latin cohaerere, meaning 'to stick together' (co- 'together' + haerere 'to cling'). The aviation meaning keeps that original sense exactly: particles of the same substance clinging to each other.
Why Pilots Care
Explains how water forms droplets, fog develops, and moisture behaves on cold surfaces, directly affecting visibility and icing risks.
Grounding Statement
A raindrop on a windshield stays rounded partly because the water is attracted to itself.
Intuition Check
Cohesion does not mean teamwork or an organized group here. It means attraction within the same substance, such as water to water or oil to oil.
Example Sentence 1
The cohesion of the fuel keeps it flowing as a continuous stream rather than breaking into droplets inside the line.
Example Sentence 2
On a cold night, cohesion helps dew form as water molecules pull together on the wing surface.