In the last few years, particularly with the widespread access to channeling, the words density or dimension have become the accepted words for the increasing levels of frequency that one would go through in one's spiritual development.
A great many sources seem to concur on what those levels are, and since their predicted phenomena actually seem to occur in my own experience, I'd say the idea definitely has merit.
These levels imply roughly the densities of consciousness, from my understanding:
First Density: Physical matter. The consciousness of atoms and molecules. Matter, energy. One dimensional awareness. Basic life forms of minerals and water are operating at this density. Within a human being the genetic structures would be first density.
Second Density: Biological matter. Plants and animals. Survival instincts and species identity. No self-consciousness or ego. Most plant and animal life exists in the second density.
Third Density: Separate individual identity, loss of group identity. Ego. Sense of linear time. Ability to remember the past and conjecture about the future. Development through time. This has been the current state of humanity. It includes an illusion of separateness and therefore an incentive to pursue higher development.
Fourth Density: Encompassing group or global consciousness while maintaining individual identity. More fluid perception of time. Interfacing with multi-dimensional realities. Polarities and individual isolation becoming more difficult to maintain. Superconsciousness.
Fifth Density: Non physical. Not bound by linear time. One reconnects with parts of one self from various levels of awareness. Ability to be operate consciously from many viewpoints simultaneously. Experiential awareness of "I" as a group identity.
Sixth Density: Total remembrance of one's existence. Operating as the whole, rather than as one individual. No sub-conscious. Awareness as dimension itself.
Seventh Density: Total integration. Being all dimensions simultaneously. Operating as a mass-conscious whole.
This is obviously a kind of path. One can advance to a higher level by some kind of personal or mass-conscious development. Each level means a higher frequency, a step closer to ones true nature as source. A higher 'density' doesn't mean 'more heavy' here, but just that things are speeded up, one can handle more stuff at the same time. One is more oneself.