interlocked

An interlocked object or system has its parts connected closely together, like puzzle pieces that fit snugly into each other.

Imagine trying to take apart a toy made of two perfectly fitted blocks. If they're interlocked, you'll have trouble prying them apart because their surfaces are so intricately matched. In engineering and design, this means that certain components or systems work seamlessly with each other, making it hard to separate them without causing damage.