Definitions for eccentricityˌɛk sənˈtrɪs ɪ ti, ˌɛk sɛn-

Random House Webster's College Dictionary

ec•cen•tric•i•ty^*ˌɛk sənˈtrɪs ɪ ti, ˌɛk sɛn-(n.)(pl.)-ties.

an oddity or peculiarity, as of conduct.
the quality of being eccentric.
the amount by which something is eccentric.
a mathematical 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.
Category: Math

^* Syn: eccentricity , peculiarity , quirk , idiosyncrasy all refer to some deviation in behavior, style, or manner from what is or expected. eccentricity usu. suggests a mildly amusing but harmless characteristic or style: a whimsical eccentricity of dress.peculiarity is the most general of these words, referring to almost any perceptible oddity or departure from any norm: a peculiarity of the language.quirk often refers to a minor, unimportant kind of oddity: Her one quirk was a habit of writing long, rambling letters. 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.

Origin of eccentricity:

1545–55; < ML

Princeton's WordNet

eccentricity(noun)
strange and unconventional behavior
eccentricity(noun)
(geometry) a ratio describing the shape of a conic section; the ratio of the distance between the foci to the length of the major axis
"a circle is an ellipse with zero eccentricity"
eccentricity(noun)
a circularity that has a different center or deviates from a circular path

Kernerman English Learner's Dictionary

eccentricity(noun)ˌɛk sənˈtrɪs ɪ ti, ˌɛk sɛn-
the state of being eccentric, or sth that makes you eccentric
my grandfather's eccentricity; His love of shiny red objects was one of his eccentricities.

Wiktionary

eccentricity(Noun)
The quality of being eccentric; any eccentric behaviour.
eccentricity(Noun)
The ratio, constant for any particular conic section, of the distance of a point from the focus to its distance from the directrix

Webster Dictionary

Eccentricity(noun)
the state of being eccentric; deviation from the customary line of conduct; oddity
Eccentricity(noun)
the ratio of the distance between the center and the focus of an ellipse or hyperbola to its semi-transverse axis
Eccentricity(noun)
the ratio of the distance of the center of the orbit of a heavenly body from the center of the body round which it revolves to the semi-transverse axis of the orbit
Eccentricity(noun)
the distance of the center of figure of a body, as of an eccentric, from an axis about which it turns; the throw