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 baseline of drinks included here is pretty generous, from coffee and soft drinks, to cocktails and wine. — Condé Nast, Condé Nast Traveler, 23 Sep. 2026

Lockheed Martin is continuing work on additional versions while increasing production of the baseline missile. — Kaif Shaikh, Interesting Engineering, 22 Sep. 2026

Use them the way the researchers used them, hydrated, time-limited and with a clear read on your own cardiovascular baseline. — Samantha Agate, Kansas City Star, 22 Sep. 2026

Each measure is compared against a preindustrial baseline, or the period before humans began burning fossil fuels in earnest—roughly the mid-19th century. — Andrea Thompson, Scientific American, 21 Sep. 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