n. Deviation from a center; the state of a circle with reference to its center not coinciding with that of another circle.n. In geometry and astronomy, the distance between the foci of a conic divided by the transverse diameter. The eccentricity of the earth's orbit is .01677, or about .n. In ancient astronomy, the distance of the center of the equant from the earth.n. Departure or deviation from that which is stated, regular, or usual; oddity; whimsicalness: as, the eccentricity of a man's genius or conduct.n. An eccentric action or characteristic; a striking peculiarity of character or conduct.n. Also excentricity in the literal uses.