Vacuum is not the only English word containing a double u (i.e. uu).
There exists another non-related term with the said feature, used both in mathematics and in music.

Find it and others (there are several words, mostly derived from Latin).

(In reply to Plurals, plurals, plurals by JayDeeKay)

The reminds me of a headling in a small story in the New York Times several years ago (maybe about 5 years), concerning courses in Latin being included in school curricula. A search shows it was published October 7, 2008, and had the headline

Latin Returns from the Dead in School Curriculums.

The irony of the combination of the subject with the form of the plural was amusing and disturbing. I do note that dictionaries, in their describivist rather than prescriptivist phases allow some of these to be of the -s variety, including curriculums and vacuums, but not continuums (at least in the Random House dictionary).

I do also see that the NY Times has changed the heading, when you actually click on the above title, to

A Dead Language That's Very Much Alive

even though the link that gets you there still has the ironic print headline.

Posted by Charlie on 2013-05-31 12:46:13