<p><strong>Adjective:</strong></p><ul><li>happening every two years: biennial games.</li><li>lasting or enduring for two years: a biennial life cycle.</li><li>Botany: completing its normal term of life in two years, flowering and fruiting the second year, as beets or winter wheat.</li></ul><p><strong>Noun:</strong></p><ul><li>any event occurring once in two years.</li><li>Botany: a biennial plant.</li></ul>