Interpersonal is about what happens between people, not inside one person. Schools and workplaces love it: interpersonal skills are talking, listening, and getting along. A doctor can be very clever and still be weak at interpersonal work if patients do not feel heard. It is a fairly formal, textbook-sounding word — you would put it in a report more than in a chat with friends, who would just say ‘good with people’. Though actually, it is not only about being nice. An argument is interpersonal too, because two people are in it. A fight, a kindness, a quiet look: if it runs from one person to another, this word can cover it.