The name of the library seems Windows specific, since DLL is the term that Windows uses for shared libraries. Would not Boost DLM ( for dynamic loadable modules ) or Boost Loadable Library be clearer ?
If I remember correctly, there was a long discussion about the naming of the library before the majority seemed ok with DLL because it's explicitely only about loading libraries, not "modules"(which is misleading)
nor "plugins" (which would require a lot more features).
The name, if my memory is correct, was not particularly thought to be about the Windows context.
Other libraries also already took the other names like Boost.SharedObject so it was not an option.