Question

Based on the definition of the prefix, what does the underlined word mean?

once a year
twice a year
twice a month
every other year

Answer 1

Every other year.

Explanation: the prefix bienn-/bi- means “two” and -ennial relates to years, so biennial means occurring every two years. (Note: biannual often causes confusion — it usually means twice a year, while biennial = every two years.)