Cambridge dictionary of American English - Sidney I. Landau

The authoritative guide to American English as it's really used today.
Based on the Cambridge International Corpus, a database that includes more than 200 million words of spoken and written American English, the paperback edition contains more than 40,000 definitions of words and phrases. Entries are organized by meaning, and words with more than one meaning are clearly marked with a boxed guideword, so there's no guesswork involved in finding the right entry. Definitions are written using a carefully controlled 2,000-word defining vocabulary, so they are clear and easy to understand. The dictionary also includes coverage of important Canadian and British words and meanings.