Tooth, tooth, other words that begin with tooth include: toothbrush, toothpaste, toothless, etc.

Ache refers to persistent, not very intense pain, that is, dull pain, which often forms compound words with organs, such as: backache, headache, earache, etc.

We all know that the plural form of tooth is teeth, so have you ever wondered why toothache is Toothache instead of teethache?

Actually, this is a rule of English compound words. There is such a kind of English compound words: usually it is an object A+a noun B, and finally it is a noun B..

For example, glasses-Eyeglass presents a mirror, and the eyes are just a supplementary explanation. Similarly, there are: footwear, earphone, bookcase, etc. Do you think this is the truth?

These things, such as bookshelves, there must be more than one book in them, but they are not bookshelves but bookshelves, because in the end, there is a case-shelf, and there is only one shelf.

The reason why glasses are usually said to be eyeglasses is that glass refers to a single lens, and a glass is usually composed of two lenses, so it is eyeglasses.

Then let's go back to toothache, because the final expression is ache-pain, and tooth only supplements the painful part, so it's toothache instead of teeache, isn't it simple?

After understanding the basic rules, everyone must know why toothbrushes with many teeth are toothbrushes instead of teethbrush. Congratulations ~

English explanation of toothbrush:

pain caused by something being wrong with one of your teeth。