[front line] n (1917) 1 a: a military line formed by the most advanced tactical combat units; also: front 2a(2) b: an area of potential or actual conflict or struggle
2: the most advanced, responsible, or visible position in a field or activity
[front line] n (1917) 1 a: a military line formed by the most advanced tactical combat units; also: front 2a(2) b: an area of potential or actual conflict or struggle
2: the most advanced, responsible, or visible position in a field or activity
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012