It's totally arbitrary which key you press to close a window.

你可以按下任意键去关闭的一个窗口。

youdao

His choices are totally autonomous, or arbitrary, or random. Cf.

人的选择是完全自主的，随意的，任意的。

youdao

Later in the term, we'll see why we have this syntax and why it wasn't just a totally arbitrary Python brain-dead decision by the designers of Python, and many languages before Python, but in fact is a pretty sensible thing.

这个学期的晚些时候,我们会去学学我们学这些语法的原因,以及这些语法其实并不是,和以前其他语言的设计者，一拍脑子做出的决定，实际上制定这些语法其实是相当明智的。

麻省理工公开课 - 计算机科学及编程导论课程节选