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

Be wary of a company that promotes a small green program while staying quiet about its total emissions, or announces a goal with no baseline, timeline or annual progress to check it against. — Christopher Elliott, Forbes.com, 2 Aug. 2026

Yet, trapped within the GOP apparatus, his baseline scenario has always been a predictable squeeze in the primary, caught between conservative purists who view him as too centrist and partisan Democrats who hold the financial high ground. — Dain Fitzgerald, The Washington Examiner, 1 Aug. 2026

Whittingham’s baseline for success in Year 1 might strike some Michigan fans as underwhelming. — Austin Meek, New York Times, 31 July 2026

The Shaded Seats blog suggests the shadiest seats at Sutter Health Park are behind home plate and along the third baseline, which become increasingly shaded during the afternoon at the ballpark. — Don Sweeney, Sacbee.com, 31 July 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