Definition
A rigid metal link in a reciprocating engine that joins a piston to the crankshaft, transmitting the piston's straight-line (reciprocating) motion to the crankshaft and converting it into rotary motion.
Plain English
A strong metal arm that connects each piston to the spinning crankshaft, so the up-and-down push of the piston turns into the round-and-round motion that drives the propeller.
Context Anchor
Seen when studying the main internal parts of a spark ignition reciprocating engine.
Why Pilots Care
Transfers combustion force from each piston to the crankshaft; failure can stop the engine or cause catastrophic internal damage.
Analogy
Think of your leg pushing a bicycle pedal. Your lower leg acts like a connecting rod: it pushes straight down, but because it's hinged to the pedal, that straight push becomes a circular motion at the crank.
Intuition Check
Do not read “connecting rod” as just any rod that connects two airplane parts. In this engine context, it specifically means the link between the piston and the crankshaft.
Example Sentence 1
Each piston is linked to the crankshaft by its own connecting rod.
Example Sentence 2
Mechanics check connecting-rod bearings for wear during a top overhaul because play here reduces engine smoothness.