This newly updated edition of America's favorite dictionary features revised biographical and geographical entries as well as up-to-date charts and tables for topics such as world currencies and chemical elements. Among the 500 entries new to this update are Amber Alert, blogosphere, gravitino, halo effect, hawala, lycopene, malware, micropolis, proteome, Qi Gong, SARS, shout-out, speed dating, sudoku, Texas hold'em, text message, and wiki. The renowned American Heritage Usage Panel, a group of more than 200 distinguished writers, scholars, and scientists, offers advice on problems of grammar and style; engaging notes explain word histories and clarify differences among synonyms; thousands of quotations and example sentences show words in context; and elegant definitions are enhanced by 4,000 full-color photographs, drawings, and maps, making this one of the most readable dictionaries available anywhere. This dictionary can also be purchased with a fully loadable Windows / Mac CD-ROM that contains the entire text of the updated Fourth Edition, 68,000 audio pronunciations, 1,000 full-color photographs and illustrations, and a college-level thesaurus with more than 260,000 synonyms. The CD-ROM has spell-check capability and can be used in conjunction with any Microsoft Office application to get definitions at the click of a mouse.