The term 'front line' can refer to a variety of different contexts. In military terms, it is the line of troops that are closest to the enemy and are most likely to engage in combat. In business, it is the employees who are in direct contact with customers and are responsible for providing customer service. In the medical field, it is the healthcare workers who are on the front lines of the fight against disease and illness. The crossword solution for this term is 'Isobar', which is a line on a map connecting points of equal atmospheric pressure. This line is used to track weather patterns and predict storms.