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

Jordan Walsh drew an offensive foul to force a turnover, pump-faked a three to evade a Phoenix defender, then drove baseline for a slam. —Zack Cox, Boston Herald, 25 Feb. 2026

And while that may be the hill on which negotiations devolve, the baseline contention by the MLB Players Association is that the problem is not every owner is trying to win. —Kevin Acee, San Diego Union-Tribune, 24 Feb. 2026

Anthropic describes the index as an early baseline rather than a final verdict. —Sheryl Estrada, Fortune, 24 Feb. 2026

Countries like Singapore and Australia that were paying the 10% baseline tariff before will also be subject to higher 15% tariffs. —Miranda Jeyaretnam, Time, 24 Feb. 2026

Word History

First Known Use

circa 1556, in the meaning defined at sense 1

Rhymes for baseline

• acridine
• alkaline
• andesine
• anodyne
• anticline
• arginine
• asinine
• atropine
• benzidine
• borderline
• byzantine
• calamine

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