Origin

This character combines wood on the left with a component on the right that hints at pronunciation. A hinge or pivot is fundamentally a wooden piece — the kind of wooden bar that holds a door in place and lets it swing. The right component tells you roughly how the character sounds, while the wooden radical tells you it's something made of wood. Together they create the image of that central wooden pivot point around which a door rotates, which is why the character came to mean both the physical hinge and the idea of a center or pivot point more broadly.