It's clear that several people want to fix problems with the in-built dictionary. Why won't the developers at least condescend to give us some sort of answer? We DON'T want to be able to change it ourselves, but we would like a developer to change it where it is justified.

This is open source software, and you are asking in a support forum for assistance with development (creating dictionaries. Perhaps ask in a developer forum if you want answers about developer topics.

The dictionaries are huspell formatted files and you can find a discussion here http://pwet.fr/man/linux/fichiers_speciaux/hunspell/ The chromium project also offers some information on editing hunspell files.https://www.chromium.org/developers/how-tos/editing-the-spell-checking-dictionaries I think you will quickly get the idea that is is not really for the feint of heart. I would not recommend it as it is messy, but of course you can do it.

There does appear to be a lot of dictionaries available already. https://addons.thunderbird.net/en-US/thunderbird/search/?q=dictionary&appver=&platform=

Why would you want to correct the one that is installed?

It seems perfectly reasonable to me to ask in a support forum for support. I specifically say that I don't ask for permission to edit the dictionary - that would cause chaos if lay users could do it. All I am asking for is for someone to delete the entry 'eth', which is not an English word, from the dictionary. It seems to me to be a legitimate request, and one that is simple to implement. I certainly have no wish to take on a task which should be reserved for the developers.

In the attached picture you can see that 'eth' and 'teh' are flagged as misspelled, according to the EN-US or EN-CA dictionaries. If teh is selected, eth doesn't appear in the context menu of suggested replacements.

So, I don't see how there is any defect in these dictionaries, at least in this example.

I have the British English dictionary. I have now seen a request for funding from the author, so perhaps if I send him $1miilion, he will fix it. (I didn't say 'US dollars')

Interestingly, eth is a word in the English language. It is also specific to Old English. So I would guess it has a place in an EN_GB Dictionary.

eth or edh noun a letter in the form of a crossed d, written đ or ð, used in Old English writing to represent both voiced and unvoiced th and in modern Icelandic and in phonetic alphabets to represent voiced th. Source https://www.dictionary.com/browse/eth

How many times have you used that word in the last 1000 years?

I contacted the compiler of the British English dictionary and he has kindly agreed to remove the word.

The compiler can be contacted through https://www.marcoagpinto.com/mainmenu.html