the point at which a bar, or something that is balancing, is supported or balances

A seesaw balances at its fulcrum. 跷跷板在支点处保持平衡。

the main thing or person needed to support something or to make it work or happen

The fulcrum of the debate/argument is the individual's right to choose. 辩论／争论的中心点在于个人进行选择的权利。