WordWeb is a one-click English thesaurus and dictionary for Windows that can look up words in almost any program. It works off-line, but can also look up words in web references such as the Wikipedia encyclopedia. Features of the free version include:

Definitions and synonyms
Related words
5000 audio pronunciations
65 000 text pronunciations

150 000 root words
120 000 synonym sets
Look up words in almost any program

Millions of people from all over the world use this top-rated software.

While installing, if ask for install any thirdparty Addon ,toolbars or change browser settings user can skip or select a custom install.

Title : WordWeb8.0
Filename : wordweb8.exe
File size : 21.5213M
Requirements : Windows 2000 / XP / Vista / Windows7 / XP64 / Vista64 / Windows7 64 / Windows8 / Windows8 64
Languages : Multiple languages
License : Freeware
Date added : 2015-11-06
Author : WordWeb Software

•  Changes: 

- Thousands of new and revised definitions
- Fast and reliable one-click lookup in the latest Firefox, Chrome and Edge browsers
- Updated for Windows 10 and one-click in most Windows 10 store apps
- Improved one-click and keyboard lookup, including in Thunderbird and FireFox (no plugin required)
- Improved suggestions for misspellings
- Web reference embedded browser support for more modern sites
- Option to set the default dictionary to be a custom web reference