deviation from what is ordinary or customary, as in conduct or manner; oddity; unconventionality
an eccentric trait or habit; peculiarity
Math. the ratio of the distances from any point of a conic section to the focus and to the directrix: the value of this ratio determines the type of conic section (zero = circle, between zero and one = ellipse, one = parabola, more than one = hyperbola)
Mech. the distance between the center of a shaft and the center of its eccentric wheel: sometimes, erroneously, called a throw