stra ‧ tum /ˈstrɑːtəm $ ˈstreɪ-/ BrE AmE noun ( plural strata /-tə/) [countable]
[ Date: 1500-1600 ; Language: Modern Latin ; Origin: Latin , 'something spread, bed' , from sternere 'to spread out' ]
1 . a layer of rock or earth
2 . a social class in a society:
people of different social strata