Underground Economy: An expression used to describe all market exchange that goes unreported either because it is illegal or because those involved want to evade taxes.
www.crfonline.org/orc/glossary/u.html
"The underground economy refers to both legal activities, such as often found in construction and service industries where taxes are not withheld and paid, and illegal activities, such as drug dealing and prostitution."
http://www.washingtontimes.com/news/2009/dec/09/new-underground-economy/
Gray economy (shadow economy): Consists of business activities that are not accounted for by official statistics. It includes illegal activities (or the so-called black market) and activities that are in themselves legal but go unreported or under-reported for purposes of tax evasion.
http://www.worldbank.org/depweb/english/beyond/global/glossary.html
The term gray economy […] refers to workers being paid under the table, without paying income taxes or contributing to such public services as Social Security and Medicare. It is sometimes referred to as the underground economy or "hidden economy."
http://en.wikipedia.org/wiki/Grey_market
black economy: a hidden sector of the economy where private cash transactions go unreported; "no one knows how large the black economy really is"
http://wordnetweb.princeton.edu/perl/webwn?s=black economy
www.crfonline.org/orc/glossary/u.html
"The underground economy refers to both legal activities, such as often found in construction and service industries where taxes are not withheld and paid, and illegal activities, such as drug dealing and prostitution."
http://www.washingtontimes.com/news/2009/dec/09/new-underground-economy/
Gray economy (shadow economy): Consists of business activities that are not accounted for by official statistics. It includes illegal activities (or the so-called black market) and activities that are in themselves legal but go unreported or under-reported for purposes of tax evasion.
http://www.worldbank.org/depweb/english/beyond/global/glossary.html
The term gray economy […] refers to workers being paid under the table, without paying income taxes or contributing to such public services as Social Security and Medicare. It is sometimes referred to as the underground economy or "hidden economy."
http://en.wikipedia.org/wiki/Grey_market
black economy: a hidden sector of the economy where private cash transactions go unreported; "no one knows how large the black economy really is"
http://wordnetweb.princeton.edu/perl/webwn?s=black economy