MERRIAM-WEBSTER ONLINEDictionary, thesaurus, Spanish-English dictionary, medical dictionary and a basic encyclopedia, all searchable free of charge.
OXFORD ENGLISH DICTIONARY ONLINEThis link opens in a new windowAuthoritative historical record of the English Language providing definitions as well as quotations that show the evolution of meaning and usage from the first known use to the present. Complete text of the 20 volume 2nd edition.
SYMBOLS.COMAn encyclopedia of graphic symbols, with the histories, uses, and meanings of various Western signs and ideograms. The online version of Thought Signs: The Semiotics of Symbols - Western Non-Pictorial Ideograms by Carl G. Liungman.