a set of springs for the support of a mattress.

What is a Bedstring?

(ˈbɛdsprɪŋ) noun. a spring that supports a mattress.

When were box springs invented?

Of course, design trends come and go. But bed historians (yes, they exist) say the traditional box spring—patented in 1869 and evolving into a standard 9-inch-high wooden frame with steel coil springs—may never come back into fashion.