And, to me, racism is harmful actions or words motivated by a hatred of or a belief in the superiority over a race by a member of another race.
“Racism” encompasses bigotry by ethnicity (which encompasses national origin), not merely that based on the 3 classical races (Negroid, Caucasoid, Mongoloid.) In fact, “race”, as commonly used, encompasses ethnic identity groups that are not classical races, too.
Plus there are plenty of examples of Trump being racist in the narrow classical sense, but if your best defense against the charge of racism is that he’s really just a bigot in a number of dimensions that aren't technically “racial”, well, that says quite a lot on its own.
“Black guys counting my money! I hate it. The only kind of people I want counting my money are short guys that wear yarmulkes every day. … I think that the guy is lazy. And it’s probably not his fault, because laziness is a trait in blacks. It really is, I believe that. It’s not anything they can control.” Trump at first denied the remarks, but later said in a 1997 Playboy interview that “the stuff O’Donnell wrote about me is probably true.”