meg ‧ a ‧ lith /ˈmeɡəlɪθ/ BrE AmE noun [countable]
[ Date: 1800-1900 ; Language: Greek ; Origin: megas 'large' + lithos 'stone' ]
a large tall stone put in an open place by people in ancient times, possibly as a religious sign
—megalithic /ˌmeɡəˈlɪθɪk◂/ adjective