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

Claude for Life Sciences outperforms human expert baselines on a range of complex life sciences tasks including understanding, manipulating and writing laboratory experiment protocols. — Rob Toews, Forbes.com, 22 June 2026

The system aggregates sensor readings, analyzes trends, compares current measurements with historical baselines, and flags anomalies that may indicate emerging failures. — Jijo Malayil, Interesting Engineering, 22 June 2026

This prototype is also the last before the Critical Design Review (CDR), the program milestone that locks in the baseline design for certification. — Omar Kardoudi june 21, New Atlas, 21 June 2026

Investors who treat this as a passing diet fad are calibrating to a baseline that no longer exists. — Tenzin Seldon, Fortune, 21 June 2026

Word History

First Known Use

circa 1556, in the meaning defined at sense 1

Rhymes for baseline

• alkaline
• andesine
• anodyne
• anticline
• arginine
• asinine
• benzidine
• borderline
• byzantine
• calamine
• caroline
• centerline

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