Revised edition, copyright 1978, 572 pages. From the cover:
The latest version of Roget's original masterpiece of synonyms and antonyms. Revised and expanded to include over 15,000 new words, 1,500 additional entries, and 160 more categories. Easier to use--quick, convenient, no index required. More up-to-date--latest colloquial and slang terms. Essential for school, home, and office.