'Shampoo' is Hindi for 'press! knead!' — it meant head massage before it meant hair-washing.
A liquid preparation for washing the hair; also used as a verb meaning to wash the hair or clean with such a preparation.
From Hindi 'chāmpō' (चाँपो), the imperative of 'chāmpnā' (चाँपना, to press, to knead, to massage), from Sanskrit 'chapayati' (चपयति, to press, to knead). The word originally referred to a head massage, not hair-washing. British colonial officers in India encountered the practice of 'champi' (head massage with oils) and borrowed the word,
When the word first entered English in 1762, 'shampooing' meant getting a massage — not washing your hair. The shift from 'pressing muscles' to 'lathering hair' happened over about a century, as British colonials gradually associated the pleasurable Indian grooming ritual with cleanliness rather than massage. Sake Dean Mahomed, a Bengali entrepreneur, opened 'Mahomed's Indian Vapour Baths