eccentricity

American  

[ek-suhn-tris-i-tee, ek-sen-] / ˌɛk sənˈtrɪs ɪ ti, ˌɛk sɛn- /

noun

plural

eccentricities

1. an oddity or peculiarity, as of conduct.

   an interesting man, known for his eccentricities.

2. the quality of being eccentric.

   Synonyms:

   aberration, freakishness, oddness, strangeness, queerness

3. the amount by which something is eccentric.

4. Machinery. the distance between the centers of two cylindrical objects one of which surrounds the other, as between an eccentric and the shaft on which it is mounted.

5. Mathematics. a constant expressed as the ratio of the distance from a point on a conic to a focus and the distance from the point to the directrix.

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eccentricity British  

/ ˌɛksɛnˈtrɪsɪtɪ /

noun

1. unconventional or irregular behaviour

2. deviation from a circular path or orbit

3. a measure of the noncircularity of an elliptical orbit, the distance between the foci divided by the length of the major axis

4. geometry a number that expresses the shape of a conic section: the ratio of the distance of a point on the curve from a fixed point (the focus) to the distance of the point from a fixed line (the directrix)

5. the degree of displacement of the geometric centre of a rotating part from the true centre, esp of the axis of rotation of a wheel or shaft

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eccentricity Scientific  

/ ĕk′sĕn-trĭs′ĭ-tē /

1. A measure of the deviation of an elliptical path, especially an orbit, from a perfect circle. It is equal to the ratio of the distance between the foci of the ellipse to the length of the major axis of the ellipse (the distance between the two points farthest apart on the ellipse). Eccentricity ranges from zero (for a perfect circle) to values approaching 1 (highly elongated ellipses).

2. The ratio of the distance of any point on a conic section from a focus to its distance from the corresponding directrix. This ratio is constant for any particular conic section.

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Related Words

Eccentricity, peculiarity, quirk, idiosyncrasy all refer to some noticeable deviation in behavior, style, or manner from what is normal or expected. Eccentricity usually suggests a mildly amusing but harmless characteristic or style: a whimsical eccentricity in choice of clothing. Peculiarity is the most general of these words, referring to almost any perceptible oddity or departure from any norm: the peculiarity of his eyelashes, of the weather. Quirk often refers to a minor, unimportant kind of oddity: Her one quirk was a habit of speaking to strangers in elevators. Sometimes quirk has overtones of strangeness: sexual quirks. Idiosyncrasy refers to a variation in behavior or manner exclusive to or characteristic of a single individual: idiosyncrasies of style that irritated editors but often delighted readers.

Etymology

Origin of eccentricity

First recorded in 1545–55; from Medieval Latin eccentricitās, equivalent to eccentric- ( see eccentric) + -itās -ity

Explanation

Eccentricity is strange, out-of-the-ordinary, sometimes weirdly attractive behavior or dress. Sleeping with your boots on is pretty normal if you're a cowboy, but leaving them on for bedtime in your city apartment, that shows some eccentricity. Eccentricity goes back to the Greek ekkentros, meaning "off center," and when you describe people as being a little "off," you might be talking about their eccentricity or behavior that's a bit abnormal. An eccentricity might be some really small character trait, like eating all of the green food on your plate first, or a large and very obvious characteristic, as when you ride a donkey to your suburban school instead of taking the bus.

Example Sentences

One can see the attraction for writers: the insular setting, the acceptance of eccentricity, the entrenchment of the otherwise unemployable, and the ease by which one can lampoon social trends.

From The Wall Street Journal • Mar. 5, 2026

I can’t decide if it’s eccentricity, a clever psych-out-the-competition move, or just Mikaela Shiffrin being Mikaela Shiffrin.

From The Wall Street Journal • Feb. 3, 2026

His growing eccentricity, which included untied shoelaces and hair that spiked out in all directions, completed the stock image of a distracted scientist.

From Los Angeles Times • Nov. 7, 2025

"It was just the eccentricity of one particular goalkeeper in one particular moment which had a commentator rubbing his eyes in disbelief," adds Tyler.

From BBC • Sep. 6, 2025

“Or maybe we all have eccentricity in us, we just don’t have the money to show it? I’d love to take you to see the house.”

From "Americanah" by Chimamanda Ngozi Adichie

Related Words

• foible
• idiosyncrasy
• peculiarity
• quirk
• weirdness