baseline

noun

base·​line ˈbās-ˌlīn 

often attributive

1

: a line serving as a basis

especially : one of known measure or position used (as in surveying or navigation) to calculate or locate something

2

a

: either of the lines on a baseball field that lead from home plate to first base and third base and are extended into the outfield as foul lines

b

: basepath

3

: a boundary line at either end of a court (as in tennis or basketball)

4

: a usually initial set of critical observations or data used for comparison or a control

5

: a starting point

the baseline of this discussion

Synonyms of baseline

• beginning
• start
• onset
• inception
• alpha
• commencement
• launch
• threshold

Examples of baseline in a Sentence

The experiment is meant only to provide a baseline for other studies.

any year or event we use as the baseline for the Renaissance is going to be at least somewhat arbitrary

Recent Examples on the Web

Compared with previous baselines, the model achieved success rates that were 30 percent to 100 percent higher, depending on the task. — Neetika Walter, Interesting Engineering, 10 Nov. 2026

The company has visited the sites and mapped existing cutting-waste flows to establish a baseline. — Alexandra Harrell, Footwear News, 10 Nov. 2026

Gilbert-Janizek’s starting point was to simulate the development of Earth had life never arisen here, therefore providing a baseline with which to compare to exoplanets. — Keith Cooper, Space.com, 8 Nov. 2026

Instead of immediately altering its footprint to suit their growing family, the couple moved in and took their time learning the baseline rhythms of the house and noticing how the Southern California light shifted across the Pacific. — Wendy Bowman, Robb Report, 6 Nov. 2026

Word History

First Known Use

circa 1556, in the meaning defined at sense 1

Rhymes for baseline

• alkaline
• andesine
• anodyne
• anticline
• arginine
• asinine
• benzidine
• borderline
• byzantine
• calamine
• caroline
• centerline

Kids Definition

baseline

noun

base·​line ˈbās-ˌlīn 

1

: a line used as a base

2

a

: either of two straight lines on a baseball field leading from home plate to first base and third base and extending into the outfield

b

: base path

Medical Definition

baseline

noun

base·​line ˈbā-ˌslīn 

: a set of critical observations or data used for comparison or a control