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

Brandon McCoy, who scored 11 points, made a huge baseline three to crush Harvard-Westlake’s momentum. —Eric Sondheimer, Los Angeles Times, 11 Mar. 2026

If The Beauty does get a second season, though, Bella serves as a new baseline for how bad this situation could get. —Roxana Hadadi, Vulture, 10 Mar. 2026

While the magnitude of these surges varies by context, the temporal clustering of activity in both cases demonstrates that social media visibility is driven by discrete political and moral shocks rather than sustained baseline engagement. —Arnaud Kurze, The Conversation, 9 Mar. 2026

Lancaster cheerleaders perform along the baseline during a second half timeout of the Tigers' game against Austin Westlake. —Dallas Morning News, 8 Mar. 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