Definition
A pair of metal contacts inside a magneto that open and close in time with the engine's rotation. When the points open, they interrupt the flow of low-voltage current in the magneto's primary circuit, causing the magnetic field to collapse and inducing the high-voltage spark that fires the spark plug.
Plain English
A small mechanical switch inside the magneto. It snaps open at exactly the right moment to trigger the spark that fires the engine's cylinders.
Context Anchor
Seen in magneto descriptions, ignition-system maintenance, engine troubleshooting, and discussions of ignition timing on piston aircraft engines.
Derivation
From 'breaker' (something that breaks or interrupts) and 'points' (the small contact tips that touch). The name describes the job: the points are the place where the electrical circuit is broken.
Why Pilots Care
Worn, pitted, or incorrectly gapped breaker points cause weak sparks, misfires, rough running, or total ignition failure.
Analogy
Breaker points work like a very fast, precisely timed light switch: closed lets current flow, open stops it. In the ignition system, that opening action helps create the spark.
Intuition Check
Breaker points are not cockpit circuit breakers. They are small ignition contacts inside a magneto or similar ignition unit.
Example Sentence 1
The mechanic found burned breaker points in the left magneto and replaced them during the annual inspection.
Example Sentence 2
Improper breaker point gap prevented the engine from starting reliably.