This term was supplied by one of my students,  to describe the sensation one feels in the neck when the support muscles of the throat are flexed in an outward stretching direction. This is needed in the top register to create space for the voice physically to operate, and for increased ressonance of the high harmonics that create ring. Though the voice becomes very comfortable, the throat muscles are actually meant to work in quite a physical manner, though this is quite opposite to feelings of constriction.