1 definition by Marwan Juma

an externality is a cost or benefit resulting from an economic transaction that is borne or received by parties not directly involved in the transaction. Externalities can be either positive, when an external benefit is generated, or negative, when an external cost is imposed upon others
"The factor has negative externality on the environment"
by Marwan Juma June 17, 2007
Get the externality mug.