Ned Block introduced the technical sense of the term "phenomenal consciousness" (or P-consciousness) in the course of contrasting it with what he called "access consciousness". Of course since it cannot be analyzed in terms of functional or psychological notions, it is (regrettably) impossible to give a definition, but one can at least list some synonyms and point to examples. Block says:

P-consciousness is experience. P-conscious properties are experiential ones. P-conscious states are experiential, that is, a state is P-conscious if it has experiential properties. The totality of the experiential properties of a state are "what it is like" to have it. Moving from synonyms to examples, we have P-conscious states when we see, hear, smell, taste, and have pains. P-conscious properties include the experiential properties of sensations, feelings, and perceptions, but I would also include thoughts, wants, and emotions. (Block 1995, 230)

Suppose you experience the sight of a red patch or the smell of something musty. The seeing and the smelling are then states of phenomenal consciousness. Those states have a special kind of property: experiential properties. The totality of those properties define "what it is like" to have the experience-the seeing or the smelling, respectively.