biennially Definition

biennial
adj

1. Said of an event: occurring once in every two years.
2. Said especially of a plant: lasting two years.

noun

1. bot.
A plant which takes two years to complete its life cycle, germinating and accumulating food reserves in the first year, and flowering, producing seed and dying during the second year, eg carrot. See also annual, perennial.
2. An event which takes place, or is celebrated, every two years.

Derivative: biennially
adverb

Etymology: 17c: from Latin biennium two years, from annus year.

Info:

A word often confused with this one is biannual.