American Heritage Dictionary of the English Language
Over 90,000 entries feature 10.000 new words and senses, 70.000 audio word pronunciations, 900 full-page color illustrations, language notes and word-root appendixes.
Merriam-Webster Dictionary
Online version of Merriam-Webster's Collegiate Dictionary, Tenth Edition. Possibility to look up a definition, pronunciation, etymology, spelling or usage point of a word.