|soap (sōp) Pronunciation Key
A substance used for washing or cleaning, consisting of a mixture of sodium or potassium salts of naturally occurring fatty acids. Like detergents, soaps work by surrounding particles of grease or dirt with their molecules, thereby allowing them to be carried away. Unlike detergents, soaps react with the minerals common in most water, forming an insoluble film that remains on fabrics. For this reason soap is not as efficient a cleaner as most detergents. The film is also what causes rings to form in bathtubs. Compare detergent.