The crossword solution for the term 'THEY CAN BE HAIR-RAISING' is GELS, which stands for 'Gelatinous Emulsions and Liquids'. GELS are a type of colloid, which is a mixture of two or more substances that are evenly distributed throughout each other. GELS are often used in hair styling products, such as mousses, GELS, and sprays, to provide hold and texture to the hair. They can also be used to create a 'hair-raising' effect, where the hair stands up on end.