pinch - Type of seal on a vacuum tube (or low pressure gas filled) that is identical to a the pinched tube with support wires visible inside a regular filament lamp. Smaller types have an outward pinch on the entire glass tube.
pip - The remains of the small sealed tube used to evacuate air from the tube. It can be visible on the top, or the top cap wire may exit via it. Alternatively it may be "hidden" in the base connector holding the pinch or even in centre of a button base.