A hideout is a place you go so that other people will not find you. Children make a hideout in a tree or a shed when they play. Police stories talk about a criminal's hideout — a flat, a cabin, a room where someone is staying in secret. It is informal, everyday English. You can also hide out (two words) as a verb: 'They hid out in the hills.' The noun hideout writes it as one word. Though actually, people sometimes use it in a softer way, not only for danger: a quiet hideout from work or from family noise, almost like a private corner. That stretch is real, but the core idea is still a place where you are not easily found.