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

The double silhouette, the slanted title and jagged baseline of the author and subtitle add so much life and movement to this cover. —Emily Temple, Literary Hub, 11 Dec. 2025

Using 2025 as a baseline, the drop begins almost immediately. —Alice Gibbs, MSNBC Newsweek, 11 Dec. 2025

Reduce Scope 1 and 2 greenhouse gas emissions 38 percent by 2029, compared to the 2021 baseline. —Angela Velasquez, Sourcing Journal, 10 Dec. 2025

State Superintendent Jill Underly said the first year of data will serve as a baseline for student performance. —Kayla Huynh, jsonline.com, 10 Dec. 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