underline

American  

[uhn-der-lahyn, uhn-der-lahyn, uhn-der-lahyn] / ˈʌn dərˌlaɪn, ˌʌn dərˈlaɪn, ˈʌn dərˌlaɪn /

verb (used with object)

underlined, underlining

1. to mark with a line or lines underneath; underscore.

2. to indicate the importance of; emphasize, as by stressing or italicizing.

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noun

1. Printing. a caption under an illustration.

2. a line drawn under something; an underscore.

underline British  

verb

1. to put a line under

2. to state forcibly; emphasize or reinforce

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noun

1. a line underneath, esp under written matter

Other Word Forms

• underlineation noun
• underliner noun
• underlining noun

Etymology

Origin of underline

First recorded in 1715–25; under- + line ¹

Example Sentences

As if to underline the point, he wore a medallion around his neck featuring NBC’s peacock logo.

From The Wall Street Journal • Feb. 12, 2026

And a regional Super Bowl commercial from Kellogg’s Raisin Bran is set to underline the importance of dietary fiber.

From The Wall Street Journal • Feb. 6, 2026

“Recent events, like the appreciation of the euro exchange rate, underline this risk,” he added.

From Barron's • Feb. 4, 2026

The results underline how widespread microplastic pollution has become, reaching even some of the most remote marine environments on Earth.

From Science Daily • Feb. 3, 2026

But even she insisted, “I want you to underline in red that it was the cherished dream of the girls to liberate the land, but none of us wanted to fight—to kill.”

From "A Thousand Sisters" by Elizabeth Wein

Related Words

• accentuate
• highlight
• indicate
• point up
• stress
• underscore