Corrosive substances are substances that can damage tissues when they come in contact with them. Many corrosive liquids are in common use, for example, in batteries. Some are used in cleaning, for example hydrochloric acid is used in some toilet bowl cleaners. Corrosive is one of the five danger risks that a liquid can have, along with toxic, flammable, explosive, and biological hazard.
Corrosive substances are to be dealt with extreme precaution and care. They are extremely dangerous.