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

In those markets, more than 17% of homeowners who received a valuation ended up listing on the MLS within 90 days, though the company has not disclosed a comparison baseline. — Nick Lichtenberg, Fortune, 8 Aug. 2026

Only two vessels transited the Strait of Hormuz on Wednesday, down from eight a day earlier, according to Kpler vessel-tracking data, against a prewar baseline of roughly 130 to 140 daily transits. — Anniek Bao, CNBC, 7 Aug. 2026

But the film is most compelling throughout as a straightforward domestic drama, with increasingly fraught family dynamics lending proceedings a baseline of credibility even as whatever’s happening outside the house remains largely inscrutable. — Guy Lodge, Variety, 7 Aug. 2026

TrendForce reported this week that Nvidia has begun evaluating lower memory configurations for Rubin Ultra, stepping down from a 12-Hi HBM4e baseline toward 8-Hi designs at 192GB. — Jon Markman, Forbes.com, 7 Aug. 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