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 of eccentricity

• 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

In astrology, Aquarius is often celebrated for its eccentricity and offbeat charm. —Valerie Mesa, PEOPLE, 17 Jan. 2026

Ake is initially hesitant to take her eccentricities to a more structured environment, but her fraught history with one recruit, 21-year-old Caleb Mir (Sandro Rosta), changes her mind. —Aramide Tinubu, Variety, 15 Jan. 2026

And the precession of the equinox controls at what point during the year Earth receives maximum insolation, which when combined with the tilt and eccentricity can alter Earth's climate significantly. —Keith Cooper, Space.com, 15 Jan. 2026

The eccentricities of a city define it; in Lagos, transportation is one of them. —Alexis Okeowo, New Yorker, 10 Jan. 2026

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