Your guess is wrong. I'm going to rely on the better informed opinions of others and my own historical understanding for my definition of the term.

we are indefinitely detaining civilians without trial.

This isn't true (at least of these people in the detention facilities...Guantanamo Bay is a different case altogether). All people requesting asylum at the borders will all be given a trial, but we don't have enough personnel to process everyone quickly - it takes months (and even after they're allowed into the country, cases can take years to complete). We could expedite it by hiring more people to process these asylum seekers, but haven't - that is a good thing to be outraged about.

Our immigration infrastructure has been inundated by so many asylum seekers that we're not able to care for them all appropriately. This is true.

We should build better facilities and hire additional personnel, we should have counselors, teachers, medical workers, and other professionals able to handle the influx of immigrants, yes - but I firmly believe the term "concentration camps" has been altered enough by events during WWII that they shouldn't be used in this case.