Quick Summary

The Latin root word ann and its variant enn both mean “year.” These roots are the word origin of various English vocabulary words, including anniversary and centennial. The roots ann and enn are easily remembered through the words anniversary, which is the turning of another “year,” and millennium, a period of 1000 “years.”

Biannual? Biennial?

The Latin root word ann and its variant enn both mean “year.” These roots will stick in your head for “years” once you’ve finished listening to this podcast!

Let’s begin with the Latin root ann which means “year.” An anniversary is simply a celebration of the turning of yet another “year.” An annual occurrence happens once “yearly.” In contrast, a biannual event happens twice per “year.” Historians and scholars often record historical occurrences in annals, which consist of a record of events which happened usually during a specific “year’s” time.

Speaking of recording events, historical dates before the time of Christ’s birth were once commonly indicated by an “AD” appended to them. “AD” was Latin for Anno Domini, or in the “year” of the Lord, which specified any date that came after the agreed upon birth of Christ. That has now been superseded by CE, or in the “Common Era,” referring to the year 1 on.

Now let’s take a look at the variant root enn, which also means “year.” Note that enn is used instead of ann when the spelling change will make a word sound better. A millennium is a period of 1000 “years;” “millannium” just sounds strange to the ear! A centennial celebration is used to mark a 100-“year” anniversary. A bicentennial is a period of 200 “years,” whereas a sesquicentennial marks a 150-“year” anniversary of a nation. An oddity in our calendar is Leap Day, an intercalary day inserted into the calendar on a quadrennial basis, or once every four “years.” And something that happens every “year?” That’s a perennial event!

Now once again to the confusion over biannual and biennial. We’ve already learned that a biannual event occurs twice per “year,” which means that a biennial happening must occur once every two “years.” An easy way to distinguish the two is that the “a” of biAnnual comes before the “e” of biEnnial alphabetically.

Now, even if we have a hard time remembering everything that happens during the “year,” we can at least remember that words that have ann and enn in them have something to do with a “year!”

  1. anniversary: the turning of a ‘year’
  2. annual: of that which happens during a ‘year’
  3. biannual: occurring twice per ‘year’
  4. annals: record of the historical events of a ‘year’ in time
  5. Anno Domini: in the ‘year’ of the Lord
  6. millennium: a 1000-‘year’ period
  7. centennial: of a 100-‘year’ period
  8. bicentennial: of a 200-‘year’ period
  9. sesquicentennial: of a 150-‘year’ period
  10. quadrennial: happening once every four ‘years’
  11. perennial: happening through the ‘years’
  12. biennial: happening once every two ‘years’


  • superannuated

    Something that is superannuated is so old and worn out that it is no longer working or useful.

  • annual

    That which happens on an annual basis happens yearly or once every year.

  • anniversary

    An anniversary is a yearly remembrance of something important that happened in a previous year, such as a wedding or birth.

Related Word Parts

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