连锁 (lián suǒ): to interlock; to be linked; chain (store etc)

I aligned the grooves of two building blocks so they interlocked, forming a small bridge.

This chain supermarket has opened twenty branches across the city, and its business is growing bigger and bigger.

When riding a bicycle, if the chain between the front and rear gears is not interlocked properly, it will make a clattering sound.

This fraud case involves multiple provinces and cities; police discovered a chain-like criminal network behind it.