Dictionaries
General Dictionaries:
American Heritage Dictionary of the English Language
Merriam Webster Online Dictionary
Webster's 1913 Revised Unabridged Dictionary
Legal Dictionaries:
FindLaw's Online Legal Dictionary
LawInfo Legal Resources Online Dictionary
Medical Dictionaries:
Merriam-Webster's Medical Dictionary
Philosophical Dictionaries:
A Dictionary of Philosophical Terms and Names
Internet Encyclopedia of Philosophy
Larry Hauser's Mostly Modern Philosophical Gallery
Stanford Encyclopedia of Philosophy