frontline

noun

1. front(def 9).
2. the visible forefront in any action, activity, or field: TV reporters are constantly involved in the front line of events.
3. Football. front four.
4. Basketball. front court(def 2b).

adjective

1. located or designed to be used at a military front line: a front-line ambulance helicopter.
2. of, relating to, or involving the forefront in any action, activity, or field: a front-line TV reporter.
3. highly experienced or proficient in the performance of one’s duties.

noun

1. military the most advanced military units or elements in a battle
2. the most advanced, exposed, or conspicuous element in any activity or situation
3. frontline (modifier)
   1. of, relating to, or suitable for the front line of a military formationfrontline troops
   2. Britishof, relating to, or suitable for public service and business employees who are in direct contact with the publicfrontline staff
   3. to the fore; advanced, conspicuous, etcfrontline news
   4. of or relating to a country bordering on or close to a hostile country or scene of armed conflictleaders of the frontline states attended the summit