Correct spelling, explanation: biannual and biennial are often confused because they sound similar and both involve the prefix bi-, which means two. However, they have distinct meanings. Biannual means occurring twice a year. It refers to events, occurrences, or publications that happen or are produced two times within a single year. Biennial, on the other hand, means occurring every two years. It refers to events, occurrences, or activities that happen or are scheduled every other year.

Definition of biannual:
adjective, happening twice a year
The company organizes biannual sales events, offering customers significant discounts in both the spring and fall.
The medical conference is a biannual gathering where experts from around the world share their latest research findings and innovations.

Collocations with biannual:
Some most commonly used collocations include:
1. Biannual report: a regular document that provides updates, data, or information on a subject every six months.
The company releases a biannual report summarizing its financial performance and strategic initiatives every June and December.
2. Biannual meeting/conference: a gathering that occurs twice a year for discussions, presentations, or collaboration.
The biannual conference on environmental sustainability brings together experts and policymakers from around the world to discuss solutions and innovations.
3. Biannual review: an assessment or evaluation conducted every six months to assess progress or performance.
The employee’s performance is assessed through a biannual review process, which allows for feedback and goal setting twice a year.
4. Biannual event: a recurring happening that takes place twice a year, such as a festival, fair, or exhibition.
The town’s biannual street fair attracts vendors and visitors in the spring and fall, offering a variety of food, crafts, and entertainment.

Correct spelling, explanation: the terms biannual and biennial are often confused due to their similar prefixes and meanings. However, they have distinct definitions. Biannual means occurring twice a year and biennial means occurring every two years. The confusion between biannual and biennial is understandable because these words share similar prefixes (bi-) and sound alike. This similarity in spelling and pronunciation can lead to misunderstandings.