The MATE Desktop for Linux installs a Dictionary app by default (a fork of the retired GNOME Dictionary app). The apps don’t protect your privacy, and you might want to stop using them.
With the apps’ default configuration, your word queries are looked up online via an arcane old internet protocol called DICT (RFC 2229). The protocol was standardized in 1997 and it doesn’t include any encryption or other privacy protections.
So, why is this a problem for dictionary lookups?, you might ask. Some knowledge is forbidden knowledge, depending on your local authorities. For example, it is inadvisable to look up information about
abortion from within some U.S. states,
war crime in Russia, or
human rights in China.
The apps don’t warn you about their privacy implications when you launch them. They’re technically required to inform you about whom they share data with (the dictionary server providers) under the General Data Protection Regulation (GDPR) in the E.U.
The apps can be configured to use a local offline dictionary. This configuration requires setting up a DICT server and change the apps to only query your local server. You then need to maintain a server and source an up-to-date dictionary.
The GNOME Dictionary used to be a GNOME Core app. Core apps are installed automatically as default apps for the GNOME Desktop. However, you may still have the app installed if you’ve kept updating the same GNOME installation over the years. The app is also still often featured in the GNOME Software store.
The MATE Dictionary app is installed by default in Linux Mint MATE. In other Linux distributions, it’s also a dependency of the MATE Desktop meta-package. The findings in this article also apply to other DICT protocol clients such as GoldenDict.
It’s possible to set up a DICT server behind a Transport Layer Security (TLS) encryption proxy. This would provide network-interception protection and on-the-network privacy protections. The dictionary server provider would still see your queries, however. Neither GNOME Dictionary, MATE Dictionary, nor GoldenDict support the non-standard DICT over TLS set up.
You should consider the Wordbook app if you’re interested in a privacy-friendly dictionary app that works offline. However, it only supports English. It automatically downloads the WordNet dictionary the first time you launch it. The WordNet Project is retired, so the dictionary will grow more out of date over time.
For a more up-to-date online and encrypted dictionary, you can consider Quick Lookup. The app is less polished than Wordbook, but it supports 46 languages. It’s powered by Wiktionary, a Wikimedia Foundation project. You can expand and contribute to the dictionary if something is missing!