The treasurer is the person in a group who takes care of the group's money. Not the person who owns it — the person who is trusted to look after it and to say where it went. A club, a school, a church, a company, a political party: if money comes in and goes out, someone is the treasurer. The job is mostly this: keep the money safe, keep a record, pay the bills the group agreed to pay, and stand up at the meeting and report. "We had $40,000 in January. We have $31,000 now. Here is why." The word is a title, not a description of a mood or a skill. You are treasurer because a group chose you, usually by a vote, and you stop being treasurer when your turn ends. This is why it is nearly always used with 'the' or with the group's name: the club treasurer, the treasurer of the association. In American government it is also an official job title — a state has a Treasurer, and the US has a Treasury Secretary, which is the same idea grown very large. Though actually, in a small club the treasurer is often just one member who is good with numbers and did not say no fast enough, and everyone still calls them 'the treasurer' with a straight face. There is no size limit on the word.