If you are not connected to the Internet, you may want to have local dictionaries or a thesaurus. I installed the following
After install you need to
sudoedit -u root /etc/default/dictdUncomment --locale=en_US.utf-8, i.e. remove the leading # on that line.
Then go into Applications/ Office/ Dictionary and enter Edit/ Preferences/. Add a new server called "Local Host" with hostname 127.0.0.1.
In emacs, use [Ctrl]-[d] [d] [d] to look up words. If you have trouble, try first restarting your machine to ensure the daemon is there. Then check that your ~/.emacs file contains something like:
(require 'dictem)
(setq dictem-server "localhost")
(dictem-initialize)
; Ask for word, database and search strategy and show definitions found
(global-set-key "\C-cds" 'dictem-run-search)
; Ask for word, database and search strategy and show matches found
(global-set-key "\C-cdm" 'dictem-run-match)
; Ask for word and database name and show definitions found
(global-set-key "\C-cdd" 'dictem-run-define)
; Show information about DICT server
(global-set-key "\C-cd\M-r" 'dictem-run-show-server)
; Show information about the database
(global-set-key "\C-cd\M-i" 'dictem-run-show-info)
; Show a list of databases provided by DICT server
(global-set-key "\C-cd\M-b" 'dictem-run-show-databases)
(setq dictem-user-databases-alist
'(("_en-en" . ("bouvier" "gcide" "wn"))
("_unidoc" . ("man" "info" "howto" "rfc" "susv3"))
))
I did not have trouble with the Ubuntu install, anyway.