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

• beginning
• start
• onset
• alpha
• inception
• 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

Known for her dominant baseline game, Sabalenka has been in top form throughout the tournament. —Kilty Cleary, MSNBC Newsweek, 10 July 2025

Establish Baseline Measurements Before implementing any AI solution, establish baseline measurements. —Caroline Castrillon, Forbes.com, 10 July 2025

How Personality May Shape Your Workout Preferences An analysis of the data collected revealed that the big five personality traits were strong predictors of whether a person would stick with an exercise plan, which types of exercise someone enjoyed, and baseline fitness. —Emily Kay Votruba, EverydayHealth.com, 10 July 2025

The letters were posted on Truth Social after the expiration of a 90-day negotiating period with a baseline levy of 10%. —Josh Boak, Chicago Tribune, 9 July 2025

Word History

First Known Use

circa 1556, in the meaning defined at sense 1

Rhymes for baseline

• acridine
• alkaline
• andesine
• anodyne
• anticline
• arginine
• asinine
• atropine
• benzidine
• borderline
• byzantine
• calamine

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