1.
front line
The foremost line of a battle or conflict. Also used figuratively for the forefront of any activity or field.
兵士たちは前線に送られた。
The soldiers were sent to the front line.
彼は研究の最前線で活躍している。
He is active at the forefront of research.
医療の前線で働く人たちに感謝したい。
I want to thank the people working on the front lines of healthcare.
2.
weather front
A boundary between two air masses of different temperatures, as used in meteorology. Commonly heard in weather forecasts.
梅雨前線が近づいている。
The rainy season front is approaching.
前線の影響で明日は雨になる。
Due to the weather front, it will rain tomorrow.
停滞前線が日本列島の上に長くとどまり、各地で大雨となった。
A stationary front lingered over the Japanese archipelago, causing heavy rain across the country.
Sense 1 is often extended with 最 as 最前線 to mean 'the very forefront.' Sense 2 is a standard meteorology term heard daily in weather forecasts.
COMMON COLLOCATIONS:
- 最前線: the very forefront
- 梅雨前線: rainy season front
- 停滞前線: stationary front
- 寒冷前線: cold front
- 温暖前線: warm front