William Whitaker's Words - Latin Dictionary
Please Download Words and install it on your computer.
If you need to look up Latin online, you can still do so.
In Windows, The Words program operates in a command console. You can make it better by right-clicking the top left corner and changing the font, size, and colors.
William Whitaker's Macintosh program should work with OS X up to 10.7, though it might be necessary to install Rosetta, which used to come with OS X but was not always installed by default. For OS X versions 10.7 and later, try Erik Mendoza's Interpres.