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

What To Consider Instead For chronic insomnia, the American Academy of Sleep Medicine recommends CBT-I (Cognitive Behavioral Therapy for Insomnia) as a first-line treatment, ahead of supplements or medication. —Allison Palmer, Sacbee.com, 16 Apr. 2026

For chronic insomnia, the American Academy of Sleep Medicine recommends Cognitive Behavioral Therapy for Insomnia as the first-line treatment, ahead of any supplement or medication. —Allison Palmer, Fort Worth Star-Telegram, 15 Apr. 2026

For many conditions, red light is best viewed as a complementary therapy rather than a first-line treatment, Arany says. —Maria Godoy, NPR, 13 Apr. 2026

Also freshly day-to-day for Pittsburgh are first-line winger Bryan Rust, rookie Ben Kindel and first-pair defenseman Parker Wotherspoon. —Sean Gentille, New York Times, 11 Apr. 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