Stop using DICT dictionary apps (such as GNOME/MATE Dictionary)
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 pricacy, 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 democracy and 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.