/ɡreɪ ɪˈkɒnəmi/ – Phrase
Definition: Hoạt động kinh tế không chính thức.
A more thorough explanation: a UK term describing the part of the economy that is not included in official statistics, usually because it is illegal or semi-legal, and unreported or underreported for tax purposes
Example: We must improve efforts to formalize the considerable grey economy.