punch down means: A risen dough can be deflated by pressing on it with your hand. Press the dough with your hands until it swells. (in Cooking Dictionary)

What else does punch down mean?

Referring to bread dough: When dough doubles in size, or if there is a dent after pressing two fingers 1/2 inch deep into the dough with your fingertips, form a fist. Push it into the middle of the dough. Turn the dough upside down and pull the edges towards the middle. Let the dough rest for at least an hour before shaping. (in Cooking Dictionary)