emacs can lookup words in dictionaries, the simplest usage is through the function dictionary-search and confirming with y when emacs asks you whether to use dict.org (the website), i have this bound as a key:
(general-define-key :states '(normal motion) :keymaps 'override "SPC s a" 'dictionary-search)
you can also force it to use dict.org without confirmation:
(setq dictionary-server "dict.org")
or if you want to run a local dictionary server, on arch linux you'd need:
sudo pacman -S dictd yay -S dict-gcide dict-wn dict-moby-thesaurus # dicts only available in aur sudo systemctl enable dictd
and just use dictionary-search, it works with no need for further configuration.