Definition 99.6.1. Let $\mathcal{X}$ be an algebraic stack. We say $\mathcal{X}$ is quasi-compact if and only if $|\mathcal{X}|$ is quasi-compact.

In your comment you can use Markdown and LaTeX style mathematics (enclose it like $\pi$). A preview option is available if you wish to see how it works out (just click on the eye in the toolbar).