having an empty space or cavity, natural or artificial, within a solid substance; not solid; excavated in the interior; as, a hollow tree; a hollow sphere.-depressed; concave; gaunt; sunken.-reverberated from a cavity, or resembling such a sound; deep; muffled; as, a hollow roar.-not sincere or faithful; false; deceitful; not sound; as, a hollow heart; a hollow friend.-a cavity, natural or artificial; an unfilled space within anything; a hole, a cavern; an excavation; as the hollow of the hand or of a tree.-a low spot surrounded by elevations; a depressed part of a surface; a concavity; a channel.-to make hollow, as by digging, cutting, or engraving; to excavate.-wholly; completely; utterly; -- chiefly after the verb to beat, and often with all; as, this story beats the other all hollow. see all, adv.-hollo.-to shout; to hollo.-to urge or call by shouting.