I'm looking for an English Thesaurus program to use in Windows. While I could just go out a buy one, I think it would be more effective if I had a digital one which I could just swap out to while typing (also would mean more space on my desk).


  • Offline: my development computer does not connect to the internet, that mean neither the program or the installer can connect online.

  • Compatible with Windows 7: obviously my OS.

  • Not restricted to 32/64-bit: I hate this with iTunes and other installers how even if I get a 32-bit installer, just because my OS is 64-bit I can't even install it and should I upgrade my PC I may not have a 64-bit system.


  • Free: while I wouldn't mind paying I would rather it's free, we can get dictionaries for free via Notepad++ so I would assume there would be a free thesaurus program.

  • Plugin to Notepad++: since I do alot of my typing in Notepad++ it would be good if the thesaurus was like a plugin for Notepad++ which makes it float around like how the search box does, though I'm not entire fussed.

  • Compatible with Window XP: sometimes at work I do work on my laptop which is Windows XP so if I can use this thesaurus on XP as well it'll be great.


I have been using Artha now for a couple of years, and it is more than just a standard thesaurus.

It is both a dictionary as it provides the meaning(s) of entered queries, and a thesaurus because it provides synonyms, antonyms, derivatives plus a number of other relationships to your query. Even better, it allows you to follow paths through those relationships by double-clicking any word in the interface and has navigation buttons to delve backwards and forwards through your search history.

It is 100% offline because it bundles the WordNet database and as such doesn't need to connect to the internet, it is open source and thus is completely free, it supports WindowsXP and up, and is 32-bit so will run fine on both 32- and 64-bit systems.

The only thing it doesn't have that you requested is Notepad++ integration.

For the sake of disclosure: I am the packager of a portable version of Artha, but am in no way affiliated with Artha itself. I don't and can't earn anything from any download of Artha or any derivatives of it.


WordWeb is pretty good. It is free, and it runs on both 32 and 64 bit machines, with various versions of Windows (XP/Vista/7/8/10). According to the linked web page, the free version offers:

  • One-click lookup in any almost any Windows program
  • Hundreds of thousands of definitions and synonyms
  • Updated with the latest international English words
  • Works offline, or reference to Wikipedia and web references

WordWeb (source: WordWeb; click image for larger variant)

There's also an extended "Pro" version, starting at a price of about 20 Euro; additional dictionaries and word lists can be obtained as well.

This should meet most of your requirements:

  • Offline: Yes.
  • Compatible with Windows 7: Yes.
  • Not 32/64bit dependent: Just a single installer, so this is met too.
  • opt: Free? Yes, free version is available.
  • opt: XP? Yes, listed as being compatible.
  • opt: Npp? Not tested, but they state "almost any Windows program". Probably not a plugin, but should work together.

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