You know when you cross that threshold, there's no going back.
Crossing the threshold into the bathroom, she paused to look at herself in the mirror with a grimace.
He stopped at the threshold and asked in Russian whether Drubetskoy lived there.
The Porte de France is the threshold of the ancient city.
If from habit and tradition he respects a stranger within his threshold, he yet considers it legitimate to warn a neighbour of the prey that is afoot, or even to overtake and plunder his guest after he has quitted his roof.