> As far as I know that’s usually a split-phase system: You get 110V between either phase and neutral, and 220V between the phases.

We Brazilians tend to call it "110V", but it's often a three-phase system with 127V between phase and neutral and 220V between phases.

Or sometimes it's 115V from phase to neutral and 230V from phase to phase (probably a split-phase system like you said). And in that case, us Brazilians would still call the lower voltage "110V", and the higher voltage "220V".

You can't trust a Brazilian when they say the voltage is "110V" or "220V". These numbers are only an approximation, which might have been correct for some places a century or two ago.

And yes, it's a mess. Check the official list at https://www2.aneel.gov.br/aplicacoes/srd/frmConcessionaria.c... (link found at https://www.gov.br/aneel/pt-br/centrais-de-conteudos/relator...), which shows which voltages can be found in each city for the whole country. For instance, take a look at the city of São Paulo in the state of São Paulo (yes, it's the same name for the state and its capital city, this is also the case for Rio de Janeiro):

  - 115V / 230V
  - 120V / 208V
  - 127V / 220V
  - 220V / 380V
  - 220V / 440V

A Brazilian would say "110V" for all these lower voltages between 115V and 127V, and would say "220V" for all these voltages between 208V and 230V.

At least the frequency is always 60Hz (unlike the rest of South America, which uses 50Hz; we have to use HVDC links when importing or exporting electricity to the neighboring countries).