Indignant

If you are indignant, you feel angry because you think something is unfair, rude, or wrong. It’s a kind of moral anger, not just annoyance.

It comes from Latin “indignari,” meaning “to consider unworthy” or “to be offended,” from “in-” (not) and “dignus” (worthy). The original idea was that something feels so beneath what is right that it makes you upset.