Substance added to a water-cooling system (for example, that of a car) to prevent it freezing in cold weather.
The most common types of antifreeze contain the chemical ethylene glycol, or (HOCH2CH2OH), an organic alcohol with a freezing point of about -15şC/5şF.
The addition of this chemical depresses the freezing point of water significantly. A solution containing 33.5% by volume of ethylene glycol will not freeze until about -20şC/-4şF. A 50% solution will not freeze until -35şC/-31şF.