The Cassell's Latin-English Dictionary has a long history. First published in 1854, it has continued in publication under various editors and revisions to the present text, the work of D.P. Simpson, Head of the Classics Department at Eton during the middle of the twentieth century. This book remains for all but the most advanced scholars in Latin the principle Latin dictionary. Clerics, students and general readers of the classics use this volume more than any other. There are other editions (concise editions, etc.), but this is primary volume for standard use.
The dictionary has two sections, a Latin-English side, and an English-Latin side. The Latin-English side contains a primary vocabulary of classical Latin, most words used and found in writings between 200 BCE and 100 AD/CE. There are also proper nouns (names, places). Spelling was flexible in the ancient world; the spelling here follows the conventional modern spellings, with cross-references for significant variances. Words indicate definitions, declension or conjugation as appropriate, and some pronunciation guides. Latin authors are also indicated (in abbreviation) for almost every word.
The English-Latin side is primarily useful for prose composition into Latin of the classical type. Because of the natural growth of language due to progress of technology and ideas, many English words will not be found, as there are no Latin equivalents. Latin equivalent words are taken largely from Cicero, Caesar and Livy, with some additions from legal and ecclesiastical Latin.
There are additional sections for standard Latin abbreviations, the Roman calendar, bibliographies for word lists, atlases, general antiquities, and Latin language guides. This is the best choice for a Latin dictionary for almost any purpose. Even high-end scholars will want the Cassell's for ready and easy reference.