The downloadable version of all products needs a recent Java release (JVM or Java Virtual Machine) installed on all platforms in order to run properly. We recommend to keep your Java machine always updated.
Check out in this page if you need to do something about Java, depending on your operating system.
• On Lion (OS X 10.7) , Moutain Lion (OS X 10.8), Mavericks (OS X 10.9), and Yosemite (OS X 10.10) there may be no Java version provided.
In this case you need to download Java from the Apple website or from the Oracle website.
The latest Java upgrade for Lion and Mountain Lion are 64-bit only. Check that you have downloaded the proper 64-bit Mac version of the dictionary.
In case of problems with Java 7, read here.
In case of problems with Yosemite and Java 8, read here.
If you get no answer, or your Java version is below 1.6, download the latest version from and follow the instructions.
Check also that Java can be used by all users and that is installed in /usr/bin.