"difficulty" 的名词形式就是 difficulty本身。

"difficulty" 的意思包括：

困难

难题

难事

困境

艰难

费劲

辛苦

困难程度

难度

复数形式是 difficulties。

例如：

She faced many difficulties on her journey to success.

The problem is insurmountable difficulty.

They had difficulty understanding the complex instructions.