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lock·nutalso lock nut (lŏk′nŭt′)
1. A usually thin nut screwed down on another nut to prevent it from loosening.
2. A self-locking nut.
1. (Mechanical Engineering) a supplementary nut screwed down upon a primary nut to prevent it from shaking loose
2. (Mechanical Engineering) a threaded nut having a feature, such as a nylon insert, to prevent it from shaking loose