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

In the rural/suburban unit, current permanent relief employees will be converted into permanent flex employees, guaranteed a baseline of 20 hours per week. —Glenn Taylor, Sourcing Journal, 23 Dec. 2025

Now, as non-invasive treatments like Botox, fillers, laser facials, and manicures are all normalized in the mainstream, the baseline of acceptable appearances has become way more expensive — excluding people at a time of growing economic inequality as well. —Leah Dolan, CNN Money, 23 Dec. 2025

For users, that guidance acts as a baseline. —K. H. Koehler, USA Today, 23 Dec. 2025

That was considered an acceptable risk, especially since the COVID virus itself was associated with a more than 16-fold increase in the risk of myocarditis, jumping from a baseline of nine cases per 100,000 individuals to 150 cases per 100,000 individuals. —Jeffrey Kluger, Time, 22 Dec. 2025

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