Dictionary and Thesaurus:

American Sign Language Dictionary
A really interesting site and a great way to learn sign language.

Merriam-Webster Online
Based on Merriam-Webster's Collegiate(R) Dictionary.

One Look Dictionaries
Searches 159 dictionaries simultaneously for any word or phrase.

Roget's Thesaurus
The University of Chicago hosts the thesaurus.

Science and Technology Dictionary
Harcourt and Academic Press provides a dictionary to search from over 130,000 terms defined in 130 fields of science.

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