Look up words in free online dictionaries like Longman Dictionary of Contemporary English, The free dictionary, Urban Dictionary, Merriam Webster and Wiktionary. Also an option for Google definitions.
Cambridge Advanced Learner's dictionary will be added in V0.2
Select a word and right click on it to look up definition. This extension allows users to see original web page of dictionary, no custom formatting is done.
This extension needs Firefox version 3.6 or higher.