Definition
In a reciprocating engine, the distance the piston travels in the cylinder between top dead center (TDC) and bottom dead center (BDC). One stroke is a single one-way movement of the piston from one end of its travel to the other.
Plain English
How far the piston moves in one direction inside the cylinder — from the top of its travel to the bottom, or the bottom back to the top.
Context Anchor
Seen in reciprocating engine discussions, especially when describing engine size, piston travel, and the four-stroke operating cycle.
Derivation
From Old English 'strican,' meaning to move or pass through. In engine terminology, it refers to one complete pass of the piston through the cylinder.
Why Pilots Care
Stroke length, combined with bore (cylinder diameter), determines an engine's displacement — which directly affects power output. Understanding strokes is essential to understanding how a piston engine produces power and why timing of intake, compression, ignition, and exhaust matters.
Intuition Check
Stroke does not mean a medical emergency here. In this context, it means the measured travel of the piston inside the engine cylinder.
Example Sentence 1
On the compression stroke, the piston moves upward and squeezes the fuel-air mixture before ignition.
Example Sentence 2
A four-stroke engine completes its cycle through intake, compression, power, and exhaust strokes.