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

But that’s about the extent of the debate, as few would be able to discern any noticeable eccentricities or downsides to the hybrid system from the driver’s seat. —Michael Harley, Forbes.com, 22 July 2025

According to the researchers, Mars' significant orbital eccentricity, or deviation from a perfect circle, causes the atmosphere in the southern summer to circulate more energetically, creating conditions ideal for vortex formation. —Nola Taylor Tillman, Space.com, 16 July 2025

Her parents were decidedly bohemian, their home a gathering place for colorful, offbeat types, so her upbringing was steeped in art and eccentricity. —Patrick Sauer, Smithsonian Magazine, 27 June 2025

He’s got a mustache with the ends waxed, and that one slight Rip Taylor eccentricity captures his carny-barker spirit. —Owen Gleiberman, Variety, 11 June 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