Biannual is an adjective which means occurring twice a year, the adverb form is biannually. Biannual is derived from the prefix bi-, which means two, twice, double, doubly, as it comes from the Latin bi-, meaning twice, double, and annual comes from the Old French twelfth century word, annuel, which derives from the Latin annus, year.
Biennial is an adjective which means occurring every two years, or every other year. Also, a biennial plant is one that takes two years to grow from its planting to its death. The adverb form is biennially. Biennial comes from the Latin biennium, which means a two year period.
Semiannual means occurring twice a year, the adverb form is semiannually. Semiannual is derived from the prefix semi-, which means half, part, partly, twice, as it comes from the Latin semi-, meaning half, and annual, which comes from the Old French twelfth century word, annuel, which derives from the Latin annus, year. Semiannual and Biannual are interchangeable, their definitions are the same.
This edition of “New Photography,” now a biannual event, features 19 artists and collectives who demonstrate how the post-Internet flood of images affects art photography. (The New York Times)
When the decision to relocate was made, it was seen by many as a decision to shake up the biannual event by placing it in a cooler setting. (The Evening Standard)
And now, for the 31st Biennial of Graphic Arts, a model of his never-realised parliament building, a visionary design with a steep conical cupola, has been seen floating down the Ljubljana river, plated in gleaming gold. (The Financial Times)
Curated by Sarah Herda and Joseph Grima, the biennial will be headquartered at, but hardly limited to, the Beaux-Arts Chicago Cultural Center, across Michigan Avenue from Millennium Park. (The Chicago Times)
The BLM, which oversees the monument, wants to shift the walk-in lottery to a 48-hour online lottery and have the public apply twice a year for the semiannual lottery, instead of monthly. (The Gazette)
Treasury spokesman Terry Stanton said the department posts yearly estimates instead of splitting the amount between the two required semiannual reports. (The Detroit Free Press)