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 Shelton of 2025 who scrapped out wins by scrambling along the baseline and finding a way has evolved into a more assertive player. — Ava Wallace, New York Times, 14 Aug. 2026

The baseline headcount was locked in at the time the Colorado Economic Development Commission approved the award, said OEDIT spokeswoman Alissa Johnson. — Aldo Svaldi, Denver Post, 14 Aug. 2026

Connecting with a provider during pregnancy can help optimize mental health before delivery and establish a baseline. — Jen Christensen, CNN Money, 13 Aug. 2026

Retail investors have been credited with fearlessly loading up on stocks in recent years, providing a baseline of inflows that has helped the current bull market become one of the longest on record. — Alex Harring, CNBC, 12 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