WordWeb

WordWeb is an international English dictionary and thesaurus program for Microsoft Windows, iOS, Android and Mac OS X. It is partly based on the WordNet database.
Functions.
WordWeb usually resides in Windows' notification area. It is activated by holding down CTRL and right-clicking a word in almost any program. This opens the WordWeb main window, with definitions and other help. In addition to its dictionary and thesaurus features, it includes:
Information.
The thesaurus is integrated into the dictionary; synonyms, as well as detailed categorization of the relationship between words, are shown under each definition. These lists appear for each word:
Each list word can be double-clicked to jump to its entry. WordWeb keeps a history of each session, allowing users to see their previously viewed entries.
Users can also actively improve the dictionary and thesaurus by submitting errors (such as missing words/phrases/senses) and enhancement requests.
Versions.
There are two WordWeb versions: the free version (which does not have the word list, search, anagram, or customization features); and the paid version, WordWeb Pro.
WordWeb 5 added the ability to list entries from three online sources: Wikipedia, Wiktionary, and WordWeb Online. These details appear in three separate tabs. Version 6 added audio pronunciations and support for third-party Oxford and Chambers add-on dictionaries.
WordWeb 7 was mainly a content upgrade, with revised definition and sound databases, but also had significantly updated one-click support for latest browsers and 64-bit programs.
Other changes included updated audio pronunciations, improved one-click integration with other programs, better one-click 64-bit and Windows 8 program support, keyboard hotkeys for Bookmark menu items, and auto-detect support for latest third-party Concise Oxford and Merriam-Webster dictionary add-ons.
As of version 7, WordWeb required Windows Windows XP, Windows Vista, Windows 7, Windows 8 or Windows 10 (desktop).
WordWeb 8 includes one-click and keyboard lookup, including in Thunderbird and FireFox without browser plugins. Support for Windows XP was dropped.
Open-source alternative.
No version of WordWeb (including Pro) is available for Unix, however, it can be used with Wine. , a similar program which includes some of WordWeb Pro's features, is available for both Linux and Windows; a port to Macintosh is promised.
License.
Use of the free version is subject to license terms. However, it might be used by an educational institution (free of cost) for their students, even if they violate said terms.
Regions.
WordWeb is regionalized, with specific dictionaries for Australian, British, Canadian, American, Irish, New Zealand, South African, and Indian English.