Voy a dejar una mención a la "informal economy" porque aparece en tantos documentos sobre el trabajo en América Latina. Pero todos me ayudaron mucho a pensar.
Copio de
http://www.ilo.org/public/english/dialogue/ifpdial/downloads...
"The Resolution also indicated that there is no universally accurate or accepted description or definition of the term “informal conomy”, but it can be said to refer to all economic activities by workers and economic units that are – in law or in practice – not covered or insufficiently covered by formal arrangements. Their activities are not included in the law, which means that they are operating outside the formal reach of the law; or they are not covered in practice, which means that although they are operating within the formal reach of the law, the law is not applied or not enforced; or the law discourages compliance because it is inappropriate, burdensome, or imposes excessive costs."
The translation workplace 
