Shampoo

The verb shampoo originally meant a massage and comes from the Hindi word champna (to press, to knead the muscles) and Sanskrit capayati (pounds, kneads).
 
Ancient Sanskrit texts describe boiling sapindus (soapberries) with dried amla (gooseberries) and a selection of other herbs. This mixture was strained to obtain the product used during shampooing to create a phenaka, the Sanskrit word for lather.
 
The practice of shampooing was brought to England from India by British colonial officials. The verb shampoo, first seen in English in 1762, meant to massage, to rub and percuss the surface of the body to restore tone and vigor.
 
Shampoo, meaning to lather and wash the hair, is from 1860. By 1954, carpets, upholstery, pets, automobiles, and other things were being shampooed.
 
The noun shampoo meaning the act or operation of shampooing is from 1838. Shampoo as the soap for shampooing is from 1866.
 
In brief, shampoo was an activity (“I will shampoo your hair”) long before it was a product (“Could you pick up some shampoo for me while you’re at the store?”).
 
Reference: Online Etymological Dictionary, https://www.etymonline.com/
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