English has seven MUTANT PLURALS—irregular nouns that change their vowel sounds when they go from singular to plural. Because of weird language reasons, they don't form plurals normally. Those nouns are "foot", "woman", "man", "tooth", "goose", "mouse", and "louse". They become "feet", "women", "men", "teeth", "mice", and "lice".
- [Voiceover] Hello, grammarians. Welcome to Irregular Plurals, Part IV. The Mutant Plurals. (moans) Yes friends, these words have mutant superpowers in that they can transform weirdly and obnoxiously, not obeying any other rules of English pluralization. But here's the cool thing. There are only seven words that behave this way. What way? I'll explain by writing all of them down. The words are foot, woman, man, tooth, goose, mouse, louse. Looks pretty straightforward, right? The thing about these words is that none of them take s as a plural. So the plural of foot is not foots, the plural of woman is not womans, the plural of tooth is not tooths. The reason these are called mutant plurals is because the vowel sound, the ooh, or the uh, or the ah, or the ooh, or the ooh, or the ou, or the ou, turns into a different sound, turns into a different vowel sound. So the plural of foot is not foots, but feet. The plural of woman is not womans, but women. The plural of man is not mans, but men. The plural of tooth is not tooths, but teeth. The plural of goose is not gooses, but geese. The plural of mouse is not mouses, but mice. And the plural of louse is not louses, but lice. You can see that mouse and louse actually change their end spelling as well from se to ce. Even though it's the same sound, louse, lice, for whatever reason, just from some quirk of our spelling history, not only do we change the vowels used here, we also change the consonants you say. Why is this the case? I'm so glad you asked. I'm going to save that for another video. In the meantime, just these seven words. One, two, three, four, five, six, seven, are the only words in English that behave this way. So you're in luck. This is a handful of words to memorize. And provided you're not borrowing any one else' hats, ideally you won't have to worry about lice very often. That's my hope. You can learn anything. David out.