Dream meaning of hollow
To dream of something that is hollow represents the womb and nurturance. It may also symbolize some hidden secrets.
Alternatively, it may indicate that you are feeling empty, worthless, or insignificant in your waking life.

A hollow is the abstract aspect of the cavern, and the inverse of the mountain. There are many symbolic significances superimposed upon the basic sense of the hollow, such as that of the Abode of the Dead, of Memories and of the Past, with further allusions to the mother and also to the unconscious, as the link between all these different aspects.
Something that is hollow retains the outer form, but is missing the core, the substance. A dream about a hollow object can reflect a feeling that despite the fact that everything is outwardly okay, something essential is missing.