Biannual vs. Semiannual: Demystifying Meaning and Usage

, Staff Writer
Updated November 5, 2021
Calendar Schedule Planning Biannual vs Semiannual
    Calendar Schedule Planning Biannual vs Semiannual
    SpicyTruffel / iStock / Getty Images Plus
    Used under Getty Images license

You have been invited to a biannual event, but then later you see it referred to as a semiannual event. What is the difference? Explore the meanings of biannual and semiannual and when to use both terms.

Are Biannual and Semiannual Synonymous or Separate?

Biannual and semiannual are often used synonymously, meaning the same definition is applied to both. Both are adjectives that describe some event or practice.

  • biannual - happening twice a year

  • semiannual - occurring twice a year or every half-year

How to Use Biannual

The Latin prefix bi- means “two” or “twice.” Annual comes from a Medieval Latin term annualis meaning “yearly,” which itself is derived from the Latin annalis or “year.” Therefore, biannual means “twice each year.”

  • The journal is a biannual publication.

  • The biannual event was highly anticipated.

  • My family has biannual reunions.


When and How to Use Semiannual

Semi means “half,” so in the context of semiannual it literally means “half year” or every six months.

  • The festival was so popular that they made it a semiannual event.

  • The semiannual report was released on Tuesday.

  • They take a semiannual trip to the beach every June and December.

Remember the Difference Between Biannual and Semiannual

At the end of the day, biannual and semiannual can be used interchangeably. However, remembering that biannual technically means "twice a year" and semiannual means "every half year" is a small but pivotal detail when you are deciding which word to use.

  • If you publish issues of a journal in March and September, they are evenly spaced out by six months, so they are semiannual.
  • If the publication is released in March and June, it is biannual because they are released twice a year, but not every six months.

What Does Biennial Mean?

Biannual can sometimes be confused with biennial, which means “happening every other year” or “every two years.”

  • The flowers she bought are biennials.

  • The biennial film festival will be held in two years.

  • He received his biennial stipend.

What Do Biweekly and Semiweekly Mean?

Related terms that are commonly associated with biannual and semiannual are biweekly and semiweekly. Like these terms, biweekly and semiweekly can be used interchangeably and have the same meaning. However, in addition to “twice a week,” biweekly also means “every two weeks.”

  • We meet biweekly for soccer practice.

  • I receive a paycheck biweekly.

  • They go to that restaurant biweekly.

Since semi- means “half,” semiweekly indicates that something is every half week or twice a week.

  • My friend and I meet up semiweekly for coffee.

  • The group met semiweekly after school.

  • The show airs semiweekly.


Memorize the Meanings

Explore similar terms that are often used synonymously but have subtly different meanings, such as transparent, translucent and opaque. Then check out words that look similar and have the same meaning but are used slightly differently, like preventive and preventative.