If a person, a song, a film, or a piece of writing is angsty, it is full of that heavy worry and unhappiness — the feeling that life is too much and you cannot see a way through. We say it most about teenagers, and about art that sounds miserable on purpose: an angsty teenager, angsty lyrics, an angsty novel. It is informal. Friends, blogs, and music reviews use it; a careful school essay usually does not. Though actually, it can sound a little mocking, as if the feelings are a look someone put on, like black clothes and a sad playlist. You would not usually call a grieving parent angsty. It is not a medical word, and it is not a kind label to stick on someone who is really unwell. Use it when the mood is dark, self-searching, and a bit dramatic — and be careful whose shoulders you put it on.