first-line

American  

[furst-lahyn] / ˈfɜrstˈlaɪn /

adjective

1. available for immediate service, especially combat service.

   first-line troops.

2. of prime importance or quality.

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first-line British  

adjective

1. acting or used as a first resort

   first-line treatment

   first-line batsmen

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Etymology

Origin of first-line

First recorded in 1895–1900

Example Sentences

For over 60 years, metformin has been a first-line treatment for type 2 diabetes, yet scientists have not fully understood how it works.

From Science Daily • Mar. 25, 2026

This was the first of two late-stage studies for giredestrant as a first-line treatment, Roche said.

From The Wall Street Journal • Mar. 9, 2026

Ms Edwards said the 10 companies in attendance at Thursday's meeting covered a "cross section" of first-line direct suppliers, covering the "whole eco-system" of the supply chain.

From BBC • Sep. 26, 2025

Police also used a liquid known as Bluestar that is meant to be a first-line method of picking up blood stains not visible to the human eye.

From Los Angeles Times • Jun. 1, 2024

A culture showed that the bacilli from his body were resistant to all four of the drugs he’d been given, and to one other first-line antibiotic as well.

From "Mountains Beyond Mountains" by Tracy Kidder and Michael French