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[ek-ster-nal-i-tee] /ˌɛk stərˈnæl ɪ ti/
noun, plural externalities.
the state or quality of being external.
something external; an outward feature.
excessive attention to externals.
an external effect, often unforeseen or unintended, accompanying a process or activity:
to eliminate externalities such as air pollution through government regulation.
Origin of externality
1665-75; external + -ity
Related forms
nonexternality, noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for externality
  • It is perhaps the strongest instance of his externality.
  • Well, guess what, our society has accepted that externality in our transportation system.
  • externality costs for coal are a large undefined risk.
  • The authors also note the potential for a positive externality.
  • More important, junk food is not itself the source of the externality-the medical costs that arise from obesity.
  • To me, fairness would suggest taxing behaviour that poses a negative externality to everyone else.
  • These calculations miss a key externality: technology transfer.
  • Environmental regulation has been necessary to achieve this, to be sure, because pollution is indeed an externality.
  • Maintaining a house is expensive and an abandoned home imposes a negative externality on its neighbours.
  • Another way to look at this may be that the good or service has a positive externality.
British Dictionary definitions for externality


noun (pl) -ties
the state or condition of being external
something external
(philosophy) the quality of existing independently of a perceiving mind
an economic effect that results from an economic choice but is not reflected in market prices
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for externality

1713, from external + -ity.

Online Etymology Dictionary, © 2010 Douglas Harper
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