Economic Definition of underground economy. Defined.
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Term underground economy Definition: Illegal and unreported market transactions and productive activity that escape the watchful eyes of official record keepers. By most estimates, a substantial amount of productive activity takes place in the underground economy for the United States. Of course, these are only estimates because such activity, by definition, goes unreported. Were activity in the underground economy added to official activity in the "overground" economy, then gross domestic product could be boosted by as much as 25% to 50%, or more.