- a rod or link for transmitting motion and force between a rotating and a reciprocating part, as between a piston and a crankshaft.
- a rod or bar for transmitting motion, esp one that connects a rotating part to a reciprocating part
- such a rod that connects the piston to the crankshaft in an internal-combustion engine or reciprocating pump
- a similar rod that connects the crosshead of a steam engine to the crank
