1. containing no ash or very little ash; free from ash
Usage: commonly used in technical and industrial contexts
2. designed or treated to leave minimal ash residue when burned
Usage: technical usage in fuel and material science

Examples

• The ashless tobacco was marketed as a cleaner alternative.
• Engineers specified ashless lubricating oils for the precision machinery.
• This ashless coal produces less pollution when burned.
• The ashless formula reduces maintenance costs on industrial equipment.
• High-quality ashless fuels are preferred in aviation applications.