ship images. The Makin Island Raid (occurred on 17 - 18 August 1942) was an attack by the United States Marine Corps on Japanese military forces on Makin Island (now known as Butaritari Island) in the Pacific Ocean.
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.
Biannual SHOULD mean twice a year. Every two years is biennial. But my dictionaries say biannual MIGHT also mean every two years. Probably everybody is so confused about the two similar words that they don't know what biannual means.