Mall cop? You gotta be a mall a
Cop because you don't know the difference between being detained and being arrested.
Try again. The "mall cops" (well, retail security officers) work for me as contractors. I direct them on behalf of my employer, who is not their employer. I also deal with mall security and police on a regular basis since they can operate where my guys and I cannot.
I know the definition better than you it seems. "Arrest" specifically means to detain, stop, or hold back ("Arrested Development"). It has nothing to do with it being justified. It's why people routinely ask a police officer if they are being detained (if not, they are free to go; if so, they they demand the justification for the arrest).
Charging with a crime or locking up in a cell is not required for it to be called an "arrest" and therefore argued to be an "unlawful arrest." If I wrongfully detain someone in a room and that person did nothing wrong, it doesn't matter that I didn't call the cops. It's why I have to be damned sure before authorizing security to make a "stop" (there's that word again).