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

Pre-mining baseline These deep-sea viruses pose little to no threat to human health. — Mrigakshi Dixit, Interesting Engineering, 14 Oct. 2026

The document lays out a 90-day compliance agenda, which features a realistic baseline for tier visibility, entity list screening and a documentation stress test that was developed based on a real-life CBP inquiry. — Kate Nishimura, Footwear News, 13 Oct. 2026

There’s also an additional $5,768 in monthly real estate taxes, bringing the total baseline carrying costs to just under $10,000 a month. — Wendy Bowman, Robb Report, 12 Oct. 2026

As greater efficiency becomes reflected in reimbursement, what creates an advantage today can become the baseline providers are expected to meet tomorrow. — Bill Miller, Fortune, 10 Oct. 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