Catalan
clàvia 
Fastener used to prevent a wheel or other part from sliding off the axle upon which it is riding.
1
Aristotle, whose authority was paramount, remained the lynch pin of university studies, especially for logic and dialectic.
2
It's the lynch pin, he said.
3
Why not a lynch pin, which we were so carefully instructed how to inquire about in Murray's Conversation for Travellers?
4
She talks about not being beaten in the match as Becky Lynch pinned Ronda Rousey.
5
Becky Lynch & Nikki Cross vs The IICONICS Result: Lynch pins Royce for the team win.
6
Lynch pinned the era to the screen as a butterfly collector might pin one of his specimens to the wall: coolly, methodically, dispassionately.