The term 'triennium' is a nine-letter word that refers to a period of THREE years. It is derived from the Latin word 'TRES', meaning 'THREE'. The term is commonly used in various contexts, such as in politics, business, and education. For example, in politics, a triennium may refer to a THREE-year term of office for a president or other elected official. In business, it may refer to a THREE-year period of financial performance or a THREE-year plan for a company. In education, it may refer to a THREE-year degree program or a THREE-year cycle of curriculum development.