Thanks for the thanks.
For the English spell-checker which (for some bizarre reason I've never been able to fathom) people refer to as a 'dictionary' then they can be got here:
For OpenOffice:
https://extensions.openoffice.org/en/pr ... openoffice
For LibreOffice:
https://extensions.libreoffice.org/en/e ... ctionaries
They both contain the same word lists but are packaged slightly different to suit either OpenOffice or LibreOffice. The package is updated every month, usually on the first day of the month. That said, only the English GB/UK speller is regularly updated every month — and the maintainer of the overall English variants package, though not of all the English variants in the package, is the person that monthly updates new words into the GB/UK speller — the other English variant spellers are maintained by other people and can have long wait periods for their maintainers to update them with new words.
Auto update for the speller in LibreOffice is not automatic so would recommend saving the link above and checking monthly for an update version — it sometimes takes a few days for LibreOffice to make the package available so best just to check at the end of the first week of a month.