1. a thin nut screwed down tightly on another nut to prevent it from loosening
Usage: mechanical engineering
2. a nut designed with special features to resist loosening from vibration
Usage: mechanical engineering

Examples

• The mechanic tightened the locknut to secure the bolt assembly.
• Without a locknut, the vibration from the engine would loosen the connection.
• She used a locknut to prevent the wheel from coming loose during the race.
• The locknut held the adjustment screw firmly in place.
• Install the locknut finger-tight, then turn it another quarter turn with a wrench.
• The nylon insert in the locknut provides resistance against loosening.