介绍（转载自http://club.mypda.com.cn/）：

大名鼎鼎的AHD4，以翔实的词源和用法为特色，在美国的受欢迎程度和M-W系列词典有的一拼，这个版本是比较完整的版本，保留了以前几位制作过AHD的朋友在制作过程中删除的Proper Names。这本词典的解释方式类似M-W系列的词典，不适用于英文水平较低的朋友。以下介绍来自Amazon.com：

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.