ec·cen·tric·i·ty 
(ĕk′sĕn-trĭsĭ-tē)
(ĕk′sĕn-trĭsĭ-tē)n. pl. ec·cen·tric·i·ties
1.
a. The quality of being eccentric.
b. Deviation from the normal, expected, or established.
2. An example or instance of eccentric behavior.
3. Physics The distance between the center of an eccentric and its axis.
4. Mathematics 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.