baseline

American  

[beys-lahyn] / ˈbeɪsˌlaɪn /

noun

baselines plural

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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Other Word Forms

Noun Inflected Forms

• baselines
  plural

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

Housing industry experts consider 5% vacancy to be a baseline for ordinary turnover.

From Salon • Jul. 4, 2026

Wagner notes that the 5-foot-7 player’s game isn’t the flashiest, but describes her as a “silent killer” who excels at “redirecting pace, standing close to the baseline, constantly putting pressure on her opponents.”

From Los Angeles Times • Jul. 2, 2026

Additionally, drop your water heater’s baseline temperature to 120 degrees to trim secondary energy bills.

From MarketWatch • Jun. 29, 2026

There were gasps in the crowd when Sinner slipped behind the baseline during the third set and took time to return to his feet, with the umpire heading over to check on him.

From BBC • Jun. 29, 2026

Her father must have noticed as well, because after a time-out, Jackie moved to the baseline and played a more defensive strategy.

From "The Parker Inheritance" by Varian Johnson

Related Words

• control
• criterion
• guideline
• measure
• standard