I was not born in the US, so let me clarify why I'm asking such question:
In Portuguese, the word "Negro" is the correct term when referring to the race, where calling somebody "Black", the color, would be considered offensive most of the time.
So is "Negro" in America a bad, offensive word, or is it the right term when referring to the race?
Best Answer
Negro is currently considered somewhat offensive in the United States, and it's not advisable to use it if you are first learning the language.
I say "somewhat" because there are circumstances where it is still used, but those circumstances are historically and socially complex, and even Americans still struggle with those circumstances.
It's best to either look for a more neutral term - black or African-American are currently* better choices - or to avoid the reference to race except where necessary. It's also a good idea to take the cue from the person you are describing - what word, if any, would they be comfortable with you using?
*Note: racial relations and language in the US continue to evolve, and what is proper today might be offensive tomorrow.