noun
temporary boom; short-lived prosperity
Refers to a sudden, brief economic upturn or burst of business activity, often implying it will not last. Commonly used in economic or business contexts.
その地域は観光客の増加でにわか景気に沸いた。
The area experienced a temporary boom due to an increase in tourists.
にわか景気に乗って、多くの店が開店した。
Riding the short-lived prosperity, many shops opened.
Compound of にわか (sudden, temporary) and 景気 (economic conditions, business). The exact historical derivation is uncertain, but the term straightforwardly describes a sudden economic upturn.