The gaseous state of a substance as distinguished from permanent gases. A gaseous fluid may be classified as either a vapor or a gas. If it is near the region of condensation, it is called a vapor. If it is well above the region of condensation, it is called a gas. Vapors in general do not follow the ideal gas law, and engineers prefer to use tables and charts based on experimental data when working with vapors. Gases, however, may obey the ideal gas laws over a wide range of temperature and pressure.