Dictionaries

Cambridge Dictionaries Online
Includes Learner's Dictionary, Advanced Learner's Dictionary, Dictionary of American English, International Dictionary of Idioms and International Dictionary of Phrasal Verbs.

Chambers Reference Online
Includes Chambers 21st Century Dictionary, Chambers Thesaurus and Chambers Biographical Dictionary.

Language Dictionaries and Translators 
Index of online dictionaries in many languages.

Oxford English Dictionary Online (UMD Only)
The online version of the OED contains two separate texts, the complete Second Edition and the New Edition in progress.

OneLook
Searches over 6 million words indexed from almost 1000 online dictionaries.

Oxford Reference Online (UMD Only)
Contains over 100 dictionary, language reference, and subject reference works published by Oxford University
Press. Fully-indexed and cross-searchable.

Phrase Finder 
Meanings and origins of over 2,000 English sayings, phrases and idioms.

RhymeZone
Rhyming dictionary finds rhymes, synonyms, definitions. 

Symbols.com 
Contains more than 2,500 Western signs, arranged into 54 groups according to their graphic characteristics. Their
histories, uses, and meanings are discussed in 1600 articles.

Webopedia 
Online dictionary and search engine for computer and internet technology.

Merriam-Webster Online
The Merriam-Webster Dictionary with definitions and audio pronunciation links.

yourDictionary.com 
Look up general or specialized words in literally thousands of English and foreign-language dictionaries.