Noun
a coiled bedspring in a frame that is covered with cloth
Source: WordNetbox-spring
It was under my mattress, not the box spring. Source: Internet
The headboard needs a mattress and box spring or platform. Source: Internet
You don't need to dump your old box spring at the landfill. Source: Internet
You'll have to use a box spring and a thick mattress as the foot of the bed and the head board have a large gap in between. Source: Internet