My definition didn’t change: It’s just that HSR is not an inner-city thing, it’s between cities, and 100km/h are properly fast metros. HSR it’s not a metro replacement, or a streetcar replacement, it’s for travel between metro areas to across the continent but it also shouldn’t be surprising if within cities, HSR can’t go faster than your usual metro. Unless you build the corridor first and the city second, or demolish a couple of neighbourhoods, there’s just going to be too tight curves. And that’s fine HSR trains spend most of their time in cities standing in a station anyway.

My previous comment gave reasons why high speed trains are often further limited to anywhere between 10 and 80km/h in urban areas.

And that’s insanity while metros are zipping by with 100km/h. Also Acela’s track troubles are not just in urban areas, even though the worst spots are in city centres.

The first actually HSR line in the US will be in California, with a minimum track speed of 180km/h and grade separation everywhere. Not all corridors are new but none will have curly track.