Economic Definition of externalities. Defined.
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Term externalities Definition: Costs or benefits that are not included in the market price of a good because they are not included in the supply price or the demand price. Pollution is an example of an externality cost if producers aren't the ones who suffer from pollution damages. Education is an example of an externality benefit when members of society other than students benefit from a more educated population. Externality is one type of market failure that causes inefficiency.