Parley
Parley is a program for vocabulary training when learning a foreign language. A free and open source program
GoldenDict-ng
GoldenDict-ng is a dictionary search program that supports many dictionary formats. A free and open source program
OdictO
OdictO is a simple offline English dictionary application for a desktop computer
Organic Maps
Organic Maps – offline maps with navigation for travelers, hikers, cyclists and drivers based on OpenStreetMap data. A free and open source program
Spedread
Spedread is a GTK program for speed reading. A free and open source program
GNOME Graphs
GNOME Graphs – tool that allows you to plot and manipulate your data with ease. Free and open source program
Artikulate
Articulate is a program for training the pronunciation of foreign language. A free and open source program
DL: language lessons
DL: language lessons is an unofficial Linux desktop client for Duolingo. Free and open source program
Kalzium
Kalzium is a free and open source program that shows the periodic table of chemical elements (Mendeleev Table)
WebArchives
WebArchives is a free and open source web archive viewer offering the ability to view offline millions of articles from large community projects such as Wikipedia or Wikisource