In practice it would probably be best to use the terminology of the country you are visiting. A visa is a document that says “Visa” on it. Things like US ESTA,

In practice it would probably be best to use the terminology of the country you are visiting. A visa is a document that says “Visa” on it. Things like US ESTA, Schengen ETIAS, Canadian eTA, etc., are not called visas by the jurisdictions that issue them. If a country makes it easy to apply for visas online without an interview, and calls that a “visa,” then it’s a visa. Some other countries don’t have advance electronic approval, but do distinguish between visa-on-arrival and visa-free transit, and it would be advisable to follow each country’s terminology. Australia does refer to its ETA and eVisitor programs as a “visa” in official literature. Otherwise you could end up confused and say the wrong thing. For example if you arrive at the border and the officer asks “Do you have a visa?” and you answer “Yes” but only have a travel authorization, you have suddenly made a false statement and could be in trouble.