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

• alpha
• beginning
• birth
• commencement
• dawn
• day one
• genesis
• get-go
• git-go
• inception
• incipience
• incipiency
• kickoff
• launch
• morning
• nascence
• nascency
• onset
• outset
• start
• 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

What’s worse, the tools once considered sufficient, like anti-virus software and two-factor authentication, are now merely the baseline. —Chad Angle, Forbes, 18 Feb. 2025

That wasn’t the case with the Trojans, who managed to double Betts into the baseline and cut off her passing angles and often survived in single coverage by pushing the 6-foot-7 center further from the basket. —Sabreena Merchant, The Athletic, 17 Feb. 2025

Ross must set a baseline for what McDaniel must do to return. Sirianni, who was making his second Super Bowl appearance, removed all doubt about his return. —Chris Perkins, Sun Sentinel, 14 Feb. 2025

The zone extends no more than 200 nautical miles from the territorial sea baseline and is adjacent to the 12-nautical-mile territorial sea of the U.S., including Puerto Rico, Guam, American Samoa, the U.S. Virgin Islands and Northern Mariana Islands. —Andrew Freedman, Axios, 13 Feb. 2025

Word History

First Known Use

circa 1556, in the meaning defined at sense 1

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