biennium : A unit of time equal to two years. Many U.S. states, including North Carolina, elect legislators every two years and adopt budgets for this two-year period, called a biennium
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}