Hermetic is an adjective that means airtight or not affected by outside influence.
In Greek mythology, Hermes was the god of science and art. So it makes sense that the scientific discovery of an airtight tube would be credited to him. The word Hermetic is named for him.
The word is generally used in a scientific context, but it can also be used more informally as in: if we don’t want the milk to spoil, we should put it into a hermetic container. Using something airtight is the only solution.