[{"Bold_text": "adjective", "List Items": ["curved like a segment of the interior of a circle or hollow ; hollow curved.Compare convex(def1) convex(def1).", "Geometry.(of a polygon) having at least one interior angle greater than 180°.", "Obsolete. hollow ."]}, {"Bold_text": "noun", "List Items": ["a concave surface, part, line, or thing.", "Machinery.a concave piece, as one against which a drum rotates."]}, {"Bold_text": "verb (used with object)", "List Items": ["to make concave."]}]