Artha is a handy off-line thesaurus based on WordNet with distinct features like global hotkey look-up, passive desktop notifications, regular expression based search, etc.. Artha may be used as a free open-source replacement to the proprietary WordWeb Pro.

GNOME Shell: Install the "AppIndicator and KStatusNotifierItem Support" extension from the Extensions Manager, or the tray icon and application window will not be visible.

Features:

• Hotkey look-up from inside any window
• Passive notifications for seamless workflow
• Spelling suggestions for a misspelled word
• Powerful regular expressions based search
• Volume and speed adjustment