👉 Latherin is a slang term that refers to the act of washing one's hair with soap. It originated in the United States and was commonly used by women for its cleansing properties. The term "lather" typically means to rub or smear something over another object, which in this context refers to lathering up one's hair with soap. So, in essence, it is a word that describes an act of washing one's hair with soap.