eccentricity

noun

ec·​cen·​tric·​i·​ty ˌek-(ˌ)sen-ˈtri-sə-tē 

plural eccentricities

1

a

: the quality or state of being eccentric

b

: deviation from an established pattern or norm

especially : odd or whimsical behavior

2

a

: a mathematical constant that for a given conic section is the ratio of the distances from any point of the conic section to a focus and the corresponding directrix

b

: the eccentricity of an astronomical orbit used as a measure of its deviation from circularity

Synonyms

• characteristic
• trick
• trait
• idiosyncrasy
• mannerism
• quirk
• singularity
• peculiarity
• individualism
• curiosity
• oddity
• habit
• twist
• tic

Examples of eccentricity in a Sentence

Some people weren't very tolerant of his eccentricity.

Talking to her plants is one of her many eccentricities.

Recent Examples on the Web

The party is now divorced from his eccentricities, which, though appealing to some of the most radical voters, alienate the rest. —Alejandro Antonio Chafuen, Forbes.com, 13 June 2025

Her gown, a Schiaparelli spring 2025 couture runway piece designed by the maison’s creative director, Daniel Roseberry, also added an air of eccentricity to her overall style with a stiff, off-the-shoulder, crystal bodice top. —Kaleigh Werner, Footwear News, 9 June 2025

Its eccentricity is endless, with a heartfelt solo here, a zany sequence there, and a glitzy grand finale to cap it all off. —Shania Russell, EW.com, 21 Mar. 2025

In the future, northern hemisphere summer will take place when Earth is closer to the sun, as Earth's orbital elongation, or eccentricity, varies. —Keith Cooper, Space.com, 11 Mar. 2025

Word History

Etymology

borrowed from Medieval Latin excentricitāt-, excentricitās, from ecentricus, excentricus "not having the earth exactly at its center, eccentric entry 1" + Latin -itāt-, -itās -ity

First Known Use

1545, in the meaning defined at sense 1a

Rhymes for eccentricity

• authenticity
• chromaticity
• concentricity
• domesticity
• elasticity
• electricity
• iconicity
• metallicity
• multiplicity
• specificity
• synchronicity
• analyticity

Kids Definition

eccentricity

noun

ec·​cen·​tric·​i·​ty ˌek-ˌsen-ˈtris-ət-ē 

plural eccentricities

1

a

: the quality or state of being eccentric

b

: something that does not follow an established pattern, norm, or rule

especially : unusual behavior

2

: the amount by which a nearly circular path is not circular

an orbit's eccentricity