Definition of hollow-back:
(n) :
An unfilled space in something solid; a cavity, natural or artificial.
(adj) :
(of something solid) Having an empty space or cavity inside.
(n) :
(figuratively) A feeling of emptiness.
(adj) :
(figuratively) Without substance; having no real or significant worth; meaningless.
(adj) :
(figuratively) Insincere, devoid of validity; specious.
(v) :
(transitive) to make a hole in something; to excavate