Element number 6 of the periodic table of elements (electronic ground state 1s2). For a description of the various types of carbon as a solid the term carbon should be used only in combination with an additional noun or a clarifying adjective.
See also: amorphous carbon, carbon fibres, carbon material, glass-like carbon, graphitic carbon, non-graphitic carbon, pyrolytic carbon
PAC, 1995, 67, 473. 'Recommended terminology for the description of carbon as a solid (IUPAC Recommendations 1995)' on page 479 (https://doi.org/10.1351/pac199567030473)