A solid decompostion product of a natural or synthetic organic material.
If the precursor has not passed through a fluid stage, char will retain the characteristic shape of the precursor (although becoming of smaller size). For such materials the term 'pseudomorphous' has been used. Some simple organic compounds, e.g. sugar, melt at an early stage of decomposition and then polymerize during carbonization to produce chars.
PAC, 1995, 67, 473 (Recommended terminology for the description of carbon as a solid (IUPAC Recommendations 1995)) on page 484