locknut

名词 locknut:

1. supplementary nut that is screwed down on a primary nut to prevent it from loosening
   同义词：safety nut

locknut lock nut

n.（名词）
A usually thin nut screwed down on another nut to prevent it from loosening.
防松螺母：常指拧紧在另一个螺母上的防止其松动的细螺母
A self-locking nut.
自锁螺母