Urban Dictionary

Urban Dictionary is a crowdsourced online dictionary of slang words and phrases. It was founded in 1999 as a parody of Dictionary.com and Vocabulary.com by then-college freshman Aaron Peckham.

The Free Dictionary

TheFreeDictionary.com, together with TheFreeLibrary.com, is the world's most comprehensive online database of reference information.

Oxford Advanced Learner’s Dictionary

Oxford Advanced Learner's Dictionary is the largest and most trusted free online dictionary for learners of English. Quickly find clear definitions and audio pronunciations of words.

Merriam-Websters

For more than 150 years, in print and now online, Merriam-Webster has been America's leading and most-trusted provider of language information.