available for immediate service, esp. combat service
first-line troops
2.
of prime importance or quality
Word origin
[1895–1900]This word is first recorded in the period 1895–1900. Other words that entered Englishat around the same time include: cutback, frame of reference, hit-and-run, neon, slapstick
Examples of 'first-line' in a sentence
first-line
Paracetamol is the most popular first-line painkiller.
Times, Sunday Times (2016)
All had been given first-line treatment: advice to keep active, plus paracetamol.
Times, Sunday Times (2007)
That trial didn't investigate first-line treatment in early non-invasive cancer.