back·field 
/ˈbækˌfi:ld/ noun
plural back·fields /ˈbækˌfi:ld/ noun American football 1 [singular] : the area of the field that is behind the line of scrimmage
▪ a tackle made in the backfield 2 [count] : the players who line up behind the line of scrimmage
▪ The team has a strong backfield.
▪ a tackle made in the backfield
▪ The team has a strong backfield.
