Wiktionary - Open Source wiki-dictionary by the Wikimedia foundation
GoldenDict - The program has the following features: Use of WebKit for an accurate articles' representation, complete with all formatting, colors, images and links.
Google Translate - Google's free service instantly translates words, phrases, and web pages between English and over 100 other languages.
Lingoes - Lingoes is an easy and intuitive dictionary and text translation software.
LibreTranslator - Android translation app with translations from LibreTranslate
WordReference - WordReference is a free online Oxford dictionaries for Spanish, French, Italian, German and more.