1.NounA rod, inside a reciprocating engine, that connects a piston to the crankshaft.
"throw a connecting rod [ = when the reciprocating assembly flies apart, rarely]; The engine threw a connecting rod at six thousand RPM and "ventilated" the engine block, as they say."
2.NounUsed other than figuratively or idiomatically: see connecting, rod: any rod that connects two other parts.
"There's a tiny connecting rod that links the actuator to this valve."