macadam /məˈkadəm 
/ ▸ noun [mass noun] broken stone of even size, bound with tar or bitumen and used in successively compacted layers for surfacing roads and paths. – DERIVATIVES macadamed /məˈkadəmd / adjective – ORIGIN early 19th century: named after John L. McAdam (1756–1836), the British surveyor who advocated using this material.
EnglishOxford Dictionary of English
