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

My second reason for starting here is that, again, the records set a baseline, only now looking forward, to help us get the measure of what followed. —Literary Hub, 28 Jan. 2026

Nvidia remains the baseline across clouds and on premises. —Ron Schmelzer, Forbes.com, 26 Jan. 2026

That’s similar to the baseline Authorized Gaming Operator (AGO) status that MLS and other leagues set up for sports betting partners over the past decade, according to Chris Schlosser, the league’s SVP of emerging ventures. —Eben Novy-Williams, Sportico.com, 26 Jan. 2026

Using data from January 2025 as a baseline, Balboa Park museums saw a 20% to more than 50% decline in visitors depending on the day and venue. —U T Editorial Board, San Diego Union-Tribune, 24 Jan. 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