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

I’m supposed to underline that this is road-tested technology, and it’s not going to be abused or prolong the action–teams are limited to two unsuccessful challenges per game.

From The Wall Street Journal • Mar. 26, 2026

Either choice would underline the FOMC’s independence from the president in a most striking manner.

From Barron's • Feb. 25, 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

While the decision on intervention lies with Japan’s finance ministry, minutes from the BOJ’s meeting last month underline that the central bank is keeping a close eye on the yen.

From The Wall Street Journal • Jan. 28, 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