title: Eccentricity
text: # Eccentricity
  
  Eccentricity or eccentric may refer to:
  
  ## Mathematics, science and technology
  
  ### Mathematics
  
  * Off-center, in geometry
  * Eccentricity (graph theory) of a vertex in a graph
  * Eccentricity (mathematics), a parameter associated with every conic section
  
  ### Orbital mechanics
  
  * Orbital eccentricity, in astrodynamics, a measure of the non-circularity of an orbit
  * Eccentric anomaly, the angle between the direction of periapsis and the current position of an object on its orbit
  * Eccentricity vector, in celestial mechanics, a dimensionless vector with direction pointing from apoapsis to periapsis
  * Eccentric, a type of deferent, a circle or sphere used in obsolete epicyclical systems to carry a planet around the Earth or Sun
  
  ### Other uses in science and technology
  
  * Eccentric (mechanism), a wheel that rotates on an axle that is displaced from the focus of the circle described by the wheel
  * Horizontal eccentricity, in vision, degrees of visual angle from the center of the eye
  * Eccentric contraction, the lengthening of muscle fibers
  * Eccentric position of a surveying tripod, to be able to measure hidden points
  * Eccentric training, the motion of an active muscle while it is lengthening under load
  * Eccentricity, a deviation from concentricity
  
  ## Other uses
  
  * Eccentric Club, a London gentlemen's club
  * The Eccentric
  * The Eccentrics
  