Crenellations & Crenulations
I just recently learned that crenellations and crenulations aren’t the same thing! I used to think there was only one word there.
They both come from the same base word, crena, the basic meaning of which is “indentation” or “notch”. In the case of crenellation, a fortifications word, this means a notch which provides an archer with shelter and a clear line of fire, like you see on castle-tops. Here, courtesy of M. Larousse, is part of a château, with some créneaux labeled:

(By the way, look below the créneaux — you gotta admit “meurtrière” is a pretty bad-ass name for an architectural feature!)
Crenulation, on the other hand, is from “crenula”, a diminutive of crena. So it’s the word for things like scalloped seashell edges, with little notches or worn patches.
Google image search gives a nice sense of crenellation. Also crenulated and crenulation. It’s interesting that “crenulation” mainly picks up the geological sense in this search, while “crenulated” seems to pick up the biological sense more.
October 31st, 2003 at 1:33 pm
There was a discussion about “crenellations” and “crenulations” a few months ago during one of my book club meetings. It was never resolved, really. One person reasoned that since both words come from “crena” that they must mean the same thing, and we decided to leave it at that.
Now, thanks to your post, I know that this is not the case…I really would like to share this information with everyone, but I doubt that anyone will remember the original discussion at this point.
November 7th, 2007 at 1:09 am
cheers mate, writing a story for english, needed to write crenellations, spell check didnt know the word and came up with crenulations. quick google search proved that they were in fact different words. cheers again