The term 'HERMETIC' is an 8-letter crossword solution for the term 'sealed so as to be airtight'. It is derived from the Greek god Hermes, who was known for his ability to keep secrets. HERMETIC sealing is a process that involves creating an airtight seal around an object or material, preventing any air or other substances from entering or leaving. This type of sealing is often used in food packaging and medical equipment to ensure that the contents remain uncontaminated.