Definition
A short length of pipe or tubing, threaded on both ends, used to connect two fittings, valves, or hoses in a fluid or pneumatic system.
Plain English
A small piece of pipe with threads at each end, used as a connector between two other parts in a plumbing-style line.
Context Anchor
Seen in aircraft maintenance descriptions for fuel, oil, air, hydraulic, and lubrication connections.
Derivation
From the Old English 'neb' meaning a small projection or tip. In plumbing, it came to mean a short pipe stub that projects from or joins between fittings.
Why Pilots Care
A secure nipple prevents leaks in critical systems that could lead to engine failure or fire.
Intuition Check
Do not read nipple here as the everyday body-related meaning. In aircraft maintenance, it means a small projecting connector for a hose, tube, or fitting.
Example Sentence 1
The mechanic replaced a leaking nipple between the fuel filter and the firewall fitting.
Example Sentence 2
Check the hydraulic nipple for cracks before the next preflight inspection.