Is it appropriate to call a non‑Muslim a kâfir?

As I understand it, kâfir refers to someone who does not believe in Islam, whether that’s from sincere ignorance or from knowingly rejecting the truth. But I’m wondering - if not every non‑Muslim is rightly called kâfir, are there terms used in the Qur’an or hadith that describe other categories of people who aren’t Muslim? Salam - just trying to learn and use the right words without being disrespectful.