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

That’s the baseline for many news outlets to broadcast or publish a story.

From Los Angeles Times • Apr. 17, 2026

“It moves developments closer to our baseline scenario for the conflict, which envisages an end to hostilities and a normalization of shipping by the end of this month.”

From Barron's • Apr. 17, 2026

Yes, chatbots are unusually persuasive, and writers pick up model biases without even knowing it, but the baseline isn’t some platonic ideal of a perfectly objective journalist.

From Slate • Apr. 17, 2026

Having a clearer baseline will make it easier to recognize unusual patterns that might be caused by biological processes.

From Science Daily • Apr. 15, 2026

To Dr. Greenfield, the true believer, it is a crucial piece of baseline evidence.

From "A Deadly Wandering: A Mystery, a Landmark Investigation, and the Astonishing Science of Attention in the Digital Age" by Matt Richtel

Related Words

• control
• criterion
• guideline
• measure
• standard