lock nut or lock·nut EXAMPLES|WORD ORIGIN noun Machinery. a nut specially constructed to prevent its coming loose, usually having a means of providing extra friction between itself and the screw. Also called jam nut. a thin supplementary nut screwed down upon a regular nut to prevent its loosening. Liberaldictionary.com
Origin of lock nut First recorded in 1860–65 Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019 Examples from the Web for lock nut Historical Examples of lock nut
The lock-nut D holds the screw securely once the pressure is adjusted.
Alfred Seymour