- available for immediate service, especially combat service: first-line troops.
- of prime importance or quality.
Origin of first-line
First recorded in 1895–1900
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for first-line
In the first-line trenches they could see no one and felt uncertain what to do.The Birth of Yugoslavia, Volume 1
Her cottage, which was less than a mile from our first-line trenches, was partly in ruins.
Sleep is a luxury indulged in but rarely in the first-line trenches.
Was it dream or reality that you were walking about in the first-line German trenches?
He had watched their advance from the first-line British trench.
- acting or used as a first resortfirst-line treatment; first-line batsmen