Good Latin dictionaries include the "Oxford Latin Dictionary," the Lewis and Short dictionary, "Collins Latin Concise Dictionary" and "Cassell's Latin Dictionary." The University of Notre Dame hosts a solid online Latin dictionary called "William Whitaker's Words."
The Lewis and Short dictionary, officially titled "A Latin Dictionary," first appeared in 1879. While still in use by scholars, the "Oxford Latin Dictionary" replaced Lewis and Short as the most used scholarly dictionary beginning in 1933. The most recent version of the Oxford dictionary released in 2012.
The first version of the "Cassell's Latin Dictionary" appeared in the 1850s and includes updates through 1977. Though lacking the history of the other books, the Collins dictionary includes more than 160,000 definitions.