Google Translate - Google's free service instantly translates words, phrases, and web pages between English and over 100 other languages.
Reverse Dictionary - Describe a concept and get back a list of words
Mate Translate - Ultimate translation app for Mac, iOS, Chrome and many more
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.
Skype Translator - Speak another language without learning another language.
FoxType Thesaurus - Visualize similar words for _____