What does “OOM-safe” mean?

(In the context of reading about the systemd D-bus implementation called sdbus (full sdbus API here)):

What does “OOM-safe” mean?

From this blog post, by Lennart Poettering, the author of systemd and sdbus: The new sd-bus API of systemd (emphasis added):

Of the two libdbus is the much older one, as it was written at the time the specification was put together. The library was written with a focus on being portable and to be useful as back-end for higher-level language bindings. Both of these goals required the API to be very generic, resulting in a relatively baroque, hard-to-use API that lacks the bits that make it easy and fun to use from C. It provides the building blocks, but few tools to actually make it straightforward to build a house from them. On the other hand, the library is suitable for most use-cases (for example, it is OOM-safe making it suitable for writing lowest level system software), and is portable to operating systems like Windows or more exotic UNIXes.

And:

To be able to use it in systemd’s various system-level components it needed to be OOM-safe and minimal.

I don’t just want the acronym meaning, but I need that too. Expound a bit please.

Also, I don’t even know what to put for a tag here (someone please help me out and edit the question to have the right tags).

Two of my ideas on what “OOM” stand for are “Object Oriented….Mmmmm (something)” and “Out of Memory”.

Further reading on sdbus: this online markdown book here: https://gitlab.com/franks_reich/systemd-by-example#52-systemd-dbus-library-sd-bus