Definition
A device that uses the flow of one fluid (typically a high-velocity gas or liquid) to draw along, mix with, or transport a second fluid. As the primary fluid passes through a narrowed throat, its velocity increases and its pressure drops, creating suction that pulls the secondary fluid into the stream.
Plain English
A simple pump with no moving parts. A fast-moving stream of air or liquid is pushed through a narrow opening, and the suction it creates pulls a second fluid along with it.
Context Anchor
Seen in aircraft maintenance descriptions of fuel, oil, hydraulic, cooling, or vent systems where fluid or air must be pulled from one place to another.
Derivation
From the Latin 'educere', meaning 'to lead out' or 'draw out' (the same root as 'educate'). An eductor literally draws one fluid out using the flow of another.
Why Pilots Care
Many transport-category aircraft use fuel eductors to keep tank compartments full or to scavenge residual fuel. Understanding that an eductor relies on motive flow (rather than a mechanical pump) helps when interpreting fuel system schematics and abnormal fuel quantity behavior.
Analogy
Like holding a garden hose past a bucket of water and watching the fast stream pull water along with it. Nothing mechanical moves the second fluid -- the moving stream does the work.
Example Sentence 1
The fuel system uses an eductor in each main tank to keep the boost pump area full of fuel during low-fuel operations.
Example Sentence 2
During inspection, the mechanic verified the eductor nozzle was clear so fuel would continue to flow properly.