Name of this project: Sage or Sagemath?

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Wikipedia writes

SageMath (previously Sage or SAGE, "System for Algebra and Geometry Experimentation"[2]) is a mathematical software with features covering many aspects of mathematics...

However, I see that the names "Sage" and "Sagemath" are both used in the documentation files, without an apparent logic. Moreover, a few Google searches fail to return information on this name change.

Should I call this software "Sage" or "Sagemath"? Is one of the two names deprecated? Should we correct it when we see it used on the internet or on the documentation, or are both acceptable? Is there official information from the development team about this renaming?