cotter pin

noun

, Machinery.

1. a cotter having a split end that is spread after being pushed through a hole to prevent it from working loose.

cotter pin

noun

1. a split pin secured, after passing through holes in the parts to be attached, by spreading the ends
2. a tapered pin threaded at the smaller end and secured by a nut after insertion

Word History and Origins

Origin of cotter pin¹

First recorded in 1890–95

Example Sentences

The piston pin of the Mercedes is of chrome nickel steel, and is retained in the piston by means of a set screw and cotter pin.

From Project Gutenberg

Won't a cotter pin be cheaper and better in place of that nut?

From Project Gutenberg

Then replace bearings, shims and caps, draw up wheel hub tight on shaft and install cotter pin.

From Project Gutenberg

Or there may have been a little carelessness when erecting, and a cotter pin omitted.

From Project Gutenberg

On every bolt use a castellated nut and a cotter pin, or an ordinary nut and a lock washer, so the bolt will not work loose.

From Project Gutenberg