Is there any difference between semi-, demi-, and hemi-?

Semi(Latin) Demi (French) Hemi (Greek) all mean half. Like a Semicircle is half a circle, Hemisphere is half of a sphere, Demigod is half of a god. Hemisphere is a little different because I would say it implies an actual axis or an even split of something. Mathematical to an extent. Semi means half but it can also mean “somewhat” like someone saying it’s “semi-abstract” meaning partially abstract or abstract in a sense. Demi means half, but to me it implies it is less than the whole instead of just half. Like a Demigod is less than an actual god or a Demi-brigade is less than the whole brigade.

Semi is used for general and scientific words like semicircle and it means "half" or "partially". Demi is used in cultural or artistic contexts like demigod and it means "half" or "lesser" Hemi is used for scientific and technical words like hemisphere and it means "half" or "one side" If you want more examples, ask me! Thank you.

Also ask about quasi- as well, because I also don't know.

I know with hair dye, demi-permanent lasts longer than semi-permanent. So there could be a length difference between those words?

They all mean "half", although they all have particular usages where they are not interchangeable, for example: * Semi-final, never demi-final or hemi-final * Demi-glace, never semi-glace or hemi-glace * Hemiplegia, never semiplegia or demiplegia And in music specifically, all three are used in Commonwealth English to describe various note values: a semiquaver is longer than a demisemiquaver, which is longer than a hemidemisemiquaver. Semi is probably the most common if there's no set prefix for a given word. Edit: I would also endorse u/rafaelbernardo2009's answer.

The main difference is etymology. Semi- is Latin, Hemi- is French, and Demi- is Greek. The one you use is typically (but not always) related to the etymology of the word it's modifying.

You drive a semi trailer, drink a demi bottle of wine and have a hemi colectomy. Welcome to English

In English they can be used interchangeably - almost as synonyms, just to mix it up a bit in your speaking/writing

I can't believe no one's brought up the [hemidemisemiquaver](https://www.merriam-webster.com/dictionary/hemidemisemiquaver). It's a half of a half of a half of an eighth note. Edit: looks like u/Gruejay2 did.

In music the notes are smaller Some music has things like a semidemihemi which is like 1/116 of a note or something ridiculous

I think the only difference would be which roots they should be paired with. Hemi- is a Greek prefix that should be paired with Greek roots. Hence “hemisphere.” Semi- is a Latin prefix that should be paired with Latin roots. Hence “semicircle.” Demi- is a (Norman) French prefix that should be paired with French roots. Hence “demitasse.” As with all English rules, there are many exceptions.

Please like my comment, I need to ask my doubt here, thanks :)