The term ultraterrestrials refers to entities that are non-physical, non-human, of natural or supernatural origin, that are indigenous to earth.
These beings can be subtle or higher-dimensional, but what they all have in common is that they are in one way or another linked to Earth!
Examples of ultraterrestrials would be the devas of mineral and plant kingdom, or faeries.
But note that several authors use the term incorrectly as a synonym of coming from higher densities or dimensions without the aspect of being linked to Earth. This is especially the case in the literatute that argues that extraterrestrials are not extraterrestrials but ultraterrestrials in the sense of originating in higher dimensions.