castellated nut

noun

1. a tall lock nut, having on its outer face radial slits allowing for insertion of a cotter pin or wire in both the nut and a hole in its bolt, so as to prevent the nut from coming loose.

Word History and Origins

Origin of castellated nut¹

First recorded in 1900–05

Example Sentences

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