dirty float

...A type of floating exchange rate system in which policy authorities (central banks and currency authorities) buy and sell foreign currency in the foreign exchange market as needed to control exchange rate fluctuations when it is believed that undesirable fluctuations in economic policy would occur if exchange rate determination were left solely to market supply and demand. The term "float" refers to a state in which the exchange rate moves like a small boat drifting on the waves, as policy restrictions on the range of exchange rate fluctuations are removed. A float in which there is no policy control over exchange rate fluctuations is sometimes called a "clean float," and a float in which there is a strong degree of control is sometimes called a "dirty float." The latter term often includes a foreign country's accusation that policy authorities are intentionally manipulating the market to distort market trends.

*Some of the terminology that refers to "dirty float" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…変動為替相場制の一種で，為替相場の決定を市場の需給関係だけにゆだねた場合，経済政策上望ましくない変動が生じると考えられるとき，政策当局(中央銀行や通貨管理局)が適宜外国為替市場で外貨の売買を行って為替相場の変動を管理する制度を指す。フロートfloatとは，為替相場の変動範囲に対する政策的制約が外されるため，あたかも波間を漂う小舟のように為替相場が推移する状態を表現したもので，為替相場の変動に対して政策的管理がいっさい行われないものをクリーン･フロートclean float，管理の程度の強いものをダーティ･フロートdirty floatと呼ぶこともある。後者の表現には，政策当局が意図的に市場の実勢をゆがめるような操作をしているという外国側の非難の意味が含まれていることが多い。…

※「dirty float」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報