eccentricity

eccentric +‎ -ity

• (US) IPA^(key): /ˌɛk.sɛnˈtɹɪs.ɪ.ti/, [ˌɛk.sənˈtɹɪs.ə.ɾi]

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eccentricity (countable and uncountable, plural eccentricities)

1. The quality of being eccentric or odd; any eccentric behaviour.
   • 1898, Winston Churchill, chapter 5, in The Celebrity:

     Although the Celebrity was almost impervious to sarcasm, he was now beginning to exhibit visible signs of uneasiness, the consciousness dawning upon him that his eccentricity was not receiving the ovation it merited.

2. (mathematics) The ratio, constant for any particular conic section, of the distance of a point from the focus to its distance from the directrix.

   For an ellipse, the eccentricity is the ratio of the distance from the center to a focus divided by the length of the semi-major axis.

3. (astronomy) The distance of the centre of a planet's orbit from the centre of the sun.