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

The first-line treatment is trimethoprim-sulfamethoxazole, sold under the brand names Bactrim, Septra, or Cotrim. — Tom Gavin, EverydayHealth.com, 11 Aug. 2026

The communication drills are intended to encourage first-line fighters to be more self-reliant and effective in battle, experts say. — ABC News, 5 Aug. 2026

Iron supplements are a first-line treatment to improve iron deficiency. — Ayesha Gulzar, Verywell Health, 31 July 2026

Molecular biologist Soulama says that Burkina Faso has decided, like some other countries on the continent, to move toward multiple first-line therapies. — Christine Ro, Forbes.com, 23 July 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
• brucine
• byline

Medical Definition

first-line

adjective

ˈfərst-ˈlīn 

: being the preferred, standard, or first choice

first-line treatment of advanced breast cancer

compare second-line