My application needs to be able to display text in English, German, Chinese, and Korean. I would like to use a single font throughout the application. I know I could use Arial Unicode MS or Lucida Sans Unicode. But they are both very large and need to be licensed.
Is the a good font that I could use?
edit: This is a windows forms application.
First of all, Arial Unicode MS is a fallback font, it shouldn't be used explicitly. And the idea of having a single font is of much less use than most people think. Keep in mind that the scripts are already very different. You'll need Latin, sinographs and Hangul. While all those probably can be found in a single font I have found the Latin characters to be pretty ugly in comparison.
Furthermore, the operating system already knows which font it can use for which script. And mostly it does a pretty good job at choosing the right one.
It would help if you can say what kind of application we are talking about. There are big differences (for instance) between ASP.NET (accessed with random browsers from random operating systems) and forms/WPF/Win32 applications.
You cannot use the same font between Korean, Traditional Chinese and Simplified Chinese. If you do, it is immediately obvious to a native if the font is not the one for his language.