first-line

adjective

ˈfərst-ˈlīn 

: being the preferred, standard, or first choice

first-line treatment of tuberculosis

compare second-line

Synonyms of first-line

• selected
• select
• favorite
• preferred
• favored

Examples of first-line in a Sentence

surgery is usually not considered a first-line treatment for this type of cancer

Recent Examples on the Web

Now, in a new paper in the journal Cell Press Blue, researchers report that if the tissue’s first-line defenses fail, then what could have been a mild infection spirals out of control. —Veronique Greenwood, Time, 27 Feb. 2026

Metformin is the first-line medication for the treatment of type 2 diabetes. —Tom Gavin, EverydayHealth.com, 27 Feb. 2026

Tommy Novak, serving as the first-line center while captain Sidney Crosby recovers from a lower-body injury sustained at the Milan Cortina Olympics, picked up his 12th goal of the season. —CBS News, 26 Feb. 2026

Vaccines are the first-line defense to help prevent and lessen the severity of some viral infections, including covid and the flu. —The Washington Post, San Diego Union-Tribune, 24 Feb. 2026

Word History

First Known Use

1919, in the meaning defined above

Rhymes for first-line

• affine
• airline
• align
• aline
• assign
• baseline
• beamline
• benign
• bloodline
• bovine
• byline
• canine

Medical Definition

first-line

adjective

ˈfərst-ˈlīn 

: being the preferred, standard, or first choice

first-line treatment of advanced breast cancer

compare second-line