baseline

American  

[beys-lahyn] / ˈbeɪsˌlaɪn /

noun

1. Baseball. the area between bases within which a base runner must keep when running from one base to another.

2. Tennis. the line at each end of a tennis court, parallel to the net, that marks the in-bounds limit of play.

3. (in perspective drawing) a horizontal line in the immediate foreground formed by the intersection of the ground plane and the picture plane.

4. a basic standard or level; guideline.

   to establish a baseline for future studies.

5. a specific value or values that can serve as a comparison or control.

6. Typography. the imaginary line on which the bottoms of primary letters align.

7. Surveying. triangulation1

8. Electronics. a horizontal or vertical line formed on the face of a cathode-ray tube by the sweep of the scanning dot.

9. Naval Architecture. a line on the body plan or sheer plan of a hull, representing a horizontal reference plane for vertical dimensions.

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adjective

1. basic or essential.

baseline British  

/ ˈbeɪsˌlaɪn /

noun

1. surveying a measured line through a survey area from which triangulations are made

2. an imaginary line, standard of value, etc, by which things are measured or compared

3. a line at each end of a tennis court that marks the limit of play

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Etymology

Origin of baseline

First recorded in 1740–50; base ¹ + line ¹

Explanation

A baseline is an imaginary starting point or basis of comparison for something. To test how a class's performance improves over time, a researcher might begin with a baseline showing their current scores and grades. You're most likely to encounter baseline in technical or work-related writing, since it's mainly used to talk about comparing data. In land surveying, the baseline runs east and west, and all measurements and surveys are based on that main line. There's also a baseline in sports, marking certain boundaries on the field or court, including the route a baseball player takes rounding the bases toward home plate.

Example Sentences

“We’re in a new era, and in that era we need a reliable baseline fab.”

From Barron's • May 21, 2026

Walsh treats well-documented, widely accessible historical facts as if they were buried state secrets, weaponizing the baseline historical illiteracy of his audience to construct a narrative of deception.

From Salon • May 20, 2026

The economic research body forecast Swiss real GDP growth, excluding major sporting events, at 1.0% in 2026 and 1.7% in 2027 under its baseline scenario, which assumes the conflict has only a limited impact.

From The Wall Street Journal • May 18, 2026

So in subsequent years, the 2027-28 level will be the baseline below which the grant can't fall.

From BBC • May 14, 2026

They passed the ball to one of their forwards coming along the baseline and he passed it to their center.

From "Slam!" by Walter Dean Myers

Related Words

• control
• criterion
• guideline
• measure
• standard