n. - Deviation from the common rule; an irregularity; anything anomalous.
n. - The angular distance of a planet from its perihelion, as seen from the sun. This is the true anomaly. The eccentric anomaly is a corresponding angle at the center of the elliptic orbit of the planet. The mean anomaly is what the anomaly would be if the planet's angular motion were uniform.
n. - The angle measuring apparent irregularities in the motion of a planet.
n. - Any deviation from the essential characteristics of a specific type.