This can imply a wide range of this depending on the dream context. It can suggest protection, when you are under a roof or a tree. It can imply being ruled or dominated by someone, or feeling them as superior, if you are in some way underneath them – as suggested by the idiom ‘under the thumb’. It can point to your own feelings of superiority if something or someone is underneath you in some way. The idiom ‘under a cloud’ also shows how we use this word to describe being depressed or down in spirits.