Computer mice or computer mouses?

The first computer mouse (1964)

 

The English word mouse has been around longer than the English language has.  Its origin is in the Proto-Germanic word mūs, which is also a word for the rodent.  It gave rise to the Old English mous and mowse, the German Maus, and the Dutch muis.  The reason the word has the peculiar plural form of mice is due to a process known as cheshirization, where a change in the way certain sounds in a language change, but an obsolete phonological distinction gets reclassified as a new form.  To make this simpler, mice is descended from the Proto-Germanic mūsiz, which is the form of the nominative and vocative declensions of mūs.  You need not know what a declension is, except that the vocative declension no longer exists in English (not as a distinct, marked form, at least).  The only way a declension changes the modern English word mouse is when we use the possessive declension mouse’s.  Declensions are something you need to have a better grasp on if you learn modern German (and even more so if you learn Old German and Old English), but modern English makes it pretty simple for us.

The reason those “vanishing forms” are referred to as cheshirization is a reference to the Cheshire Cat in Alice in Wonderland, which disappeared bit by bit until all that remained was his smile.  This term was coined in 1991 by linguist James Matisoff.  Mice is, then, the remaining “smile” of the Cheshire Cat.  Cheshirization is also known as rephonologization, which means the exact same thing, but is not nearly as much fun.

The word has taken on a number of different meanings over time.  Mouse has always been the English word for the rodent, but it's also taken on a figurative meaning as a term of endearment, though I'm not sure I've heard anyone use it outside of centuries-old literature.  A mouse can be someone who is shy, though the adjective mousy is preferred to convey this meaning.  It can also mean a group of broken blood vessels, particularly used by boxers.  It can mean a short match used to set off a cannon.  It can be a short length of rope used by sailors in the days of the wooden navies.  It could mean a small bun of women's hair.

Most alternative meanings of mouse have vanished with changes in fashion or technology.  In light of all these varied uses of the word, it shouldn't surprise us that it got another new identity more recently, with the advent of the personal computer.  A new device for inputting data into computers debuted in 1964, invented at the Stanford Research Institute by researcher Douglas Englebart.  Englebart called his invention a mouse.  Englebart chose the name because he felt it resembled the small, furry rodent.  It has since been claimed that MOUSE is an acronym for Manually-Operated User-Selection Equipment.  While this is a pretty accurate description of what a mouse does, this is not the origin of the name of the device.  Use of the computer mouse didn't really take off until around 1981, but in the 55 years of its history, they've never really been known by any other word.

It's hard to imagine a situation where a user would need more than one mouse at a time.  Humans only have so many hands, and more than one of these devices competing to input data is just something we don't do.  But if we did have more than one of them, what would we say?  Englebart, true to his association of the device with the animal, actually pluralized it as mice.  Indeed, mice is the most common plural of the computer mouse that is used in English.  However, the Oxford English Dictionary states that both terms are acceptable.  You can say there are two computer mice, or two computer mouses.  This still doesn't apply to the animal, where mice is the only acceptable plural.