Definition
An enclosed hollow space within a structure or component, often deliberately formed to serve a specific function such as containing a fluid, gas, resonating signal, or providing clearance for moving parts.
Plain English
A hollow space inside something. In aviation, cavities are usually built on purpose — for example, to hold fuel, route air, or house equipment.
Context Anchor
Seen in aircraft maintenance, inspection, repair, and structure descriptions.
Derivation
From Latin cavus, meaning hollow. The same root gives us 'cave.' It points directly to the idea of an empty space inside something solid.
Why Pilots Care
Cavities inside wings, fuselage sections, and control surfaces can collect water, fuel vapors, or corrosion. Drain holes and inspection panels exist precisely because these hollow spaces must be checked and kept clear.
Intuition Check
Do not read cavity as just a dent, crack, or surface damage. A cavity means a hollow or empty space, whether it was designed that way or should not be there.
Example Sentence 1
The mechanic inspected the wing cavity for signs of moisture before reinstalling the access panel.
Example Sentence 2
Corrosion often starts in fuselage cavities that are difficult to reach during routine checks.