Officially, OMR is a meaningless title, like LLVM. Similar to LLVM, it once stood for something, but then we realized that it didn't actually match the project's 'charter' quite as well as we had hoped... but had grown fond of the name (also... finding new names is super hard).

Original definition was 'Open Managed Runtimes', but we can do more than just managed runtimes with OMR technology, and so that seemed to sell it short.

Doesn't seem to stand for anything (at least it's not defined in the project charter).

If I had to guess at it:

Open Meta-Runtime

But I could see how that might be misinterpreted compared to their goals. Not all cap names are acronyms?

https://projects.eclipse.org/proposals/omr