cobblestone

Cobblestone comes from Middle English cobylstone (also spelled cobyllstone, kobilstane), formed from cobble plus stone.

The facts available don't describe a shift in meaning — the word has stayed close to its literal roots as a compound naming a stone used for paving.

It shares a family resemblance with Old Norse köppusteinn and Danish kampesten, both meaning 'boulder,' suggesting a wider Germanic habit of naming big stones by stacking words together.