connecting rod

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A rod that transmits motion or power from one moving part to another, especially the rod connecting the crankshaft of a motor vehicle to a piston.

from The Century Dictionary.

• noun In engineering: The coupling-rod which connects the piston with the crank of the driving-wheel axle of a locomotive engine. See cut under locomotive.
• noun The outside coupling-rod which connects the wheels of a locomotive engine, The rod connecting the cross-head of a beam-engine with that end of the working-beam which plays over the cylinder.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any rod, in an engine, that transmits power or motion, especially one that connects a reciprocating shaft to a rotating wheel, in reciprocating engines connects piston to crankshaft

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a rod that transmits motion (especially one that connects a rotating wheel to a reciprocating shaft)