Roget's International Thesaurus, Indexed, Sixth Edition Revised & Updated 
A classic reference book that has been used by millions all over the world, Roget's International Thesaurus is the product of more than a century and a half of continuous expansion, reorganization, and improvement. Today, this book is not only the most time-tested and bestselling thesaurus ever, but, newly revised, it is also the most up-to-dateand comprehensive reflection of theEnglish language as it is currently used.
The revolutionary achievement of Dr. Peter Mark Roget's first edition in 1852 was the development of a brand-new principle: the arrangement of words and phrases according to their meanings. Dr. Roget's system brings together in one place all the terms associated with a single thought or concept; it allows a wide-ranging survey of language within a book of relatively modest size, without the space-consuming repetitions that so severely limit the scope of thesauruses arranged in a dictionary format with A-to-Z entries. This brilliant organization makes Roget's International Thesaurus both the most efficient word finder and a cutting-edge aid in stimulating thought, organizing ideas, and writing and speaking more clearly and effectively.
This revised and updated sixth edition features thousands of new words and phrases, including the newest slang words and expressions that color and inform everyday language. At the same time, it retains all of the hallmarks that have made Roget's international Thesaurus an enduring classic:
More than 330,000 words and phrases organized into 1,075 categories.
A pinpoint reference system that directs the user quickly from a comprehensive index to the numbered category of the right word. Thousands of cross-references throughout lead to other helpful categories.
Hundreds of supplemental word lists that supply the names of things which have no synonyms (measurements, wines, weapons, animals, state mottoes, and more) as well as hundreds of quotations that amplify the meanings of selected words.
Generations of students, writers, editors, and speakers have made Roget's the most popular word reference book next to the dictionary. Continuing a legacy that dates back more than 150 years, Roget's International Thesaurus is an indispensable work for everyone who wants to use the English language with clarity and precision.
Reviews
This is one of the books I've dreamed of owning for decades, but delayed because it's "weird". None of the newer, more "organized" thesauri have ever approached the classic of the field, Roget's. This revised, updated, and expanded sixth edition (with handy thumb-indices) is the best ever -- for example, I can rejoice at such delights as are found in Section 311.71:
A paddling of ducks
An orchestra of crickets
A barren of mules
An ostentation of peacocks
An aurora of polar bears
A prickle of hedgehogs
Google is getting awfully good, but there's a lot to be said for the weeding process done by a careful well educated staff of editors and proofreaders. This is such an expensive and labor-intensive process that it probably won't last much longer -- so grab the old classics like this while you still can.