Apple - Hide Siri's window on macOS Sierra

You may close the Siri window at any time by pressing the ESC key. However, I am unaware of a way to automatically close Siri after some time has passed.

Another option (besides the esc key) is cmd+..

This is useful if you're on a MacBook Pro with Touch Bar, and you're in an app where the esc has turned into something else (like while playing full-screen video).

If you've enabled "Type To Siri" and find that ESC doesn't close the window, try typing "nevermind" and hitting enter. In my case, Siri replies "ok" and the window closes.

Maybe there are some other words that have the same effect?