"Centennial" Versus "Centenary"

A recent thread about Silver Jubilee Stamps prompted me to post this thread about the term "centennial" and "centenary" since the use of those terms frequently appear on stamps.

While we all know the term "centennial" and "centenary" refers to a period of 100 years, I found it interesting to learn that the term "centennial" is predominately used in the US and Canada, with the similar term "centenary" used in other major parts of the world.

A further search revealed all of the known prefixes added to the word "centennial" or "centenary" which defines other periods of time from 1/2 year to 2000 years. I thought SCF members might find the list interesting, as I had never realized all of the time definitions that were possible by simply using a prefix to the term "centennial" (this is an abridged version taken from the details provided in a Wiki search):



Although several of the terms are rarely used, a number of them do relate to terms appearing on postage stamps as it relates to specific anniversary periods of historical events.

Though absolutely correct, I would suggest that biannual is one of those "stink words" that creates confusion or requires explanation.

Semiannual is much more descriptive, and is more likely to be understood without the need for further explanation.

Nice to know there is a word for 175 years.

Some of those are a mouthful and I will keep to saying 175th anniversary of ....

Thanks for the info.
Drew