The definition of a biennium is a period of two years.
(noun)Your two-year cell phone contract is an example of a biennium.
See biennium in Webster's New World College Dictionary
See biennium in American Heritage Dictionary 4
noun pl. bi·en·ni·ums or bi·en·ni·a (-ĕnˈē-ə)
Origin:
Origin: Latin
Origin: : bi-, two; see bi-1
Origin: + annus, year; see at- in Indo-European roots
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