Urban Dictionary - Urban Dictionary is a Web-based dictionary of slang words and phrases.

Duolingo - Duolingo is a free language learning app for iOS, Windows and Android devices. The app makes learning a new language fun by breaking learning into small lessons where you can earn points and move up through the levels. Read more about Duolingo.

Dictionary Anywhere - Dictionary Anywhere is an open-source and easy-to-use browser extension for Mozilla Firefox and Google Chrome that allows you to check definitions easily while browsing the web.

Synonymful - Improve your vocabulary and communicate like a pro.

The Online Slang Dictionary - Learn thousands of real slang words or add your own.

Fluent - Fluent is a people-based marketing platform that uses real-time, one-to-one interaction to create custom audiences and serve personalized ads that drive performance at scale.