from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun One that lives or is located outside or at the edge of a given area.
  • noun One that exists outside or at an extreme of a category, pattern, or expectation; an extreme case or exception.
  • noun A value far from most others in a set of data.
  • noun A portion of stratified rock separated from a main formation by erosion.

from The Century Dictionary.

  • noun One who does not reside in the place with which his office or duty connects him.
  • noun An outsider.
  • noun A part lying without or beyond the main body; an isolated or outlying part; specifically, in geology, a part of a stratum or group of strata, or a mass of rock of any kind, which has been left behind while that part of the formation by which it was originally surrounded, and to which it belonged, has been removed by denudation.
  • noun In zoology, that which is outlying, subtypical, or aberrant, as a genus or family of animals.

from the GNU version of the Collaborative International Dictionary of English.

  • noun One who does not live where his office, or business, or estate, is.
  • noun That which lies, or is, away from the main body.
  • noun (Geol.) A part of a rock or stratum lying without, or beyond, the main body, from which it has been separated by denudation.
  • noun (Statistics) A datum that lies significantly beyond the main cluster of data points on a graph or diagram; -- suggestive of an error in measurement.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun A person or thing away from others or outside its proper place.
  • noun geology A part of a formation separated from the rest of the formation by erosion.
  • noun statistics A value in a statistical sample which does not fit a pattern that describes most other data points; specifically, a value that lies 1.5 IQR beyond the upper or lower quartile.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun a person who lives away from his place of work
  • noun an extreme deviation from the mean


from Wiktionary, Creative Commons Attribution/Share-Alike License

From outlie +‎ -er.


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  • Used extensively in Frazier's book "Cold Mountain".

    January 12, 2007

  • In statistics, an outlier is a single observation "far away" from the rest of the data.

    February 3, 2007

  • Not to be confused with an outliar, which like an outhouse, is an small shack outside of the house where people go to tell lies.

    February 4, 2007

  • See citation on pailliard.

    September 6, 2008