When is it correct to not use the irregular form for a plural? e.g. mouses vs. mice

I seem to recall that an English teacher somewhere along the course of my education had indicated that when referencing distinct types of a word, e.g. a computer mouse and the mammal, it would be proper to refer to them as "two mouses" rather than mice.

Is that actually the case? If so, where are the lines commonly drawn - consider for example observing a Canada Goose and a Greylag Goose as a more gray area or perhaps the tooth from a mouth versus a tooth from a saw blade as something quite distinct.

Solution 1:

I don't know if there are hard and fast rules about this. With mouse it seems to be that the accepted plural is mice, but if you're talking about a computer mouse you can use mouses or mice, so you'd be safe if you always used mice

Merriam Webster:

plural also mous·es : a small mobile manual device that controls movement of the cursor and selection of functions on a computer display

Oxford English

2 (plural mice or mouses)a small handheld device which is moved across a mat or flat surface to move the cursor on a computer screen.

As far as geese are concerned, I had thought they were always geese, but apparently there's also:

3 (plural gooses) a tailor's smoothing iron.

But the plural of tooth is always teeth!

Solution 2:

The Language Instinct by Steven Pinker offers an explanation involving Walkman/Walkmans and fly out/flied out (baseball terminology), which basically says that a Walkman is not a type of man, thus it does not follow the irregular plural rules for man. Similarly, fly refers to a "fly ball", which is not a verb, so the irregular verb rules for "fly" the verb do not apply to "flied out". The full explanation is in chapter 5, titled "Words, Words, Words".

Mice versus mouses is debatable. Most people I know say "mice", and indeed it could be argued that a computer mouse is a form of mouse, as it somewhat resembles one (albeit upside down), and was named after the rodent.