Cross-link

A cross-link is a chemical bond that connects two separate molecules or polymer chains together, like a bridge holding two structures in place. In scientific contexts, cross-links are essential for creating stronger, more stable materials—for example, they're what makes rubber bouncy and durable, or help proteins maintain their three-dimensional shapes in our bodies. Scientists can also artificially create cross-links to engineer new materials with specific properties for everything from construction materials to medical implants.