What would you call 10th, 20th, 30th, 40th etc. anniversary?

It is a special anniversary because it ends with 0. Is there a name for it in English?

suggestions: round anniversary, a milestone anniversary

  • it's a good question, what about a "gem" anniversary?
    – Fattie
    Commented Oct 11, 2016 at 11:16
  • 4
    decennial Adj: occurring every ten years, Noun: a decennial anniversary. Commented Oct 11, 2016 at 11:18
  • 1
    They're often referred to as 'significant' anniversaries (though they're only significant, like a century at cricket, because people consider them so. If we used a different number base ...). However, this term also includes the 25th anniversary. Commented Oct 11, 2016 at 11:19
  • @FF Like the first, 11th, 21st ...? Commented Oct 11, 2016 at 11:20
  • 2
    I don't believe there is a common term. Most people would say something like "round anniversary" or a (slightly strained) phrase such as "a multiple of ten anniversary".
    – Hot Licks
    Commented Oct 11, 2016 at 12:14

2 Answers 2


As Fumblefingers said in the comments:

decennial Adj: occurring every ten years, Noun: a decennial anniversary.

Linked is the dictionary.com page for decennial, which lists as an example the following:

3. a decennial anniversary.


For anniversaries that are considered significant because of the "roundness" of the number of years being commemorated, I believe the most common formal term is one of your suggestions, milestone anniversary. Somewhat more common is the less-formal big anniversary1. The two are also used in conjunction, as big, milestone anniversary. However, these don't exclusively refer to anniversaries that come in multiples of ten (the other suggestion of decennial is correct for that).

The definition of "big" or "milestone" understandably varies by source and also by type of anniversary, but these typically are the first, and then multiples of 5, 10, 25, 50, 100 etc. with the smaller divisions becoming less significant as the number gets higher2. Some examples of usage:

Celebrating Those BIG Anniversaries In Style
Although Anniversaries come along every year, the majority of them aren’t thought of as that special as they are a random 3, 11, 17 years etc (although let’s face it, every year is an achievement!) However, what about those big, milestone Anniversaries, surely they deserve some extra recognition? This is what we try to achieve as part of BasketsGalore’s Anniversary Gift Baskets. As well as gift baskets to celebrate general anniversaries we also theme ones for Silver, Pearl, Ruby Golden & Diamond Anniversaries i.e 25, 30, 40, 50 and 60 year anniversaries – wow! (Baskets Galore blog)

I know compared to some couples, five years is not huge, but for us, this is our first big “milestone” anniversary. (Sarah Marier, Huffington Post column)

Milestone Anniversary (Papyrus card category; includes 25th and 50th)

Milestone Anniversary (Chattanooga Times Free Press feature; this date lists 60th, 65th, 70th, and 75th wedding anniversaries)

16 Classic Movies With Big Anniversaries In 2016 (Moviepilot; lists 10th, 15th, 20th, and 30th anniversaries)

2016 to Celebrate Two Big Anniversaries
The New Year 2016 will mark two significant anniversaries for the U.S. numismatic community. The first, and probably most important, is the 100th birthday of three of America’s most beloved coinage designs of the 20th century. . . . The New Year’s second anniversary is a bit closer to home. In 2016, PCGS will celebrate its 30th anniversary. (Mike Sherman, Professional Coin Grading Service News)

1 The term major anniversaries is actually more common than all of these, but this often refers to the significance of the event being commemorated, rather than the anniversary number. See Google Ngram here, with the usual caveats.

2 That is, the fifth anniversary is almost certainly considered a big milestone, the fifteenth perhaps less-so; by the time you get to 235 probably no one pays attention—I don't remember any big celebration in the US four years ago, for example. One caveat for this is that anniversaries near or past the expected lifetime of the person or thing being commemorated may become more significant in small denominations (i.e. a 102nd birthday and a 2nd birthday are both often treated as significant, even though a 52nd birthday passes unremarked.)

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