strata

Multiple Entries:
  strata    stratum  

Concise Oxford English Dictionary © 2008 Oxford University Press:
strata/ˈstrɑːtə/

plural form of stratum.

Concise Oxford English Dictionary © 2008 Oxford University Press:
stratum /ˈstrɑːtəm, ˈstreɪtəm/

▶noun (pl. strata /-tə/)

• 1 a layer or a series of layers of rock.

• 2 a thin layer within any structure.

• 3 a level or class of society.

– origin C16: mod. L., from L., lit. ‘something spread or laid down’, neut. past part. of sternere ‘strew’.

usage: In English, as in the original Latin, stratum is singular and its plural form is strata. It is therefore incorrect to use strata as a singular or to create the form stratas as the plural: a series of overlying strata not a series of overlying stratas, and a new stratum was uncovered not a new strata was uncovered.