A treasurer is the person responsible for running the treasury of an organization. The adjective for a treasurer is normally "tresorial". The adjective "treasurial" normally means pertaining to a treasury, rather than the treasurer.
The Treasury of a country is the department responsible for the country's economy, finance and revenue. The Treasurer is generally the head of the Treasury, although, in some countries (such as the U.K. or the U.S.) the treasurer reports to a Secretary of the Treasury, or Chancellor of the Exchequer. In Australia, the Treasurer is a senior Minister and usually the second most important member of the Government after the Prime Minister. From 1867 to 1993, the Ministry of Finance (Ontario) was called the Treasurer of Ontario.
Originally the word referred to the person in charge of the treasure of a noble; however, it has now moved into wider use. In the UK during the 17th Century, a position of Lord High Treasurer was used on several occasions as the third great officer of the Crown. Now the title First Lord of the Treasury is the official title of the British Prime Minister.
In corporations, the Treasurer is the head of the corporate treasury department. They are typically responsible for liquidity risk management, cash management, issuing debt, foreign exchange and interest rate risk hedging, securitization, oversight of pension investment management, and capital structure (including share issuance and ). They also typically advise the corporation on matters relating to corporate finance. They could also have oversight of other areas, such as the purchase of insurance.