Origin of "shampoo", the word not the practice

[Broomstick]

Why do we have the word “shampoo”?

Don’t get me wrong, it’s a cute word, and useful, but why do we have a separate word for what is basically “hair soap”?

And how did we arrive at “shampoo” instead of some other collection of sounds?

[KarlGauss]

From here:

“Shampoo,” as you may have noticed, is both a noun and a verb, and the Oxford English Dictionary defines the act of shampooing as being “to subject (the scalp) to washing and rubbing with some cleansing agent, as soap and water, shampoo powder, etc.” Yes, Virginia, there once was such a thing as “shampoo powder,” and I actually bought a can of the stuff in the late 1960s. You were supposed to dump the powder on your dry hair, comb it through, and presto, your hair would be clean and shiny. Not quite. In reality, it was a case of presto, your hair was full of greasy, gritty goop.

Oddly enough, the origin of “shampoo” has nothing directly to do with hair (and does not, puns aside, involve our modern word “sham,” meaning “phony”). “Shampoo” comes from the Hindi word “campo,” meaning “to press,” and a “shampoo,” which entered English around 1762, was originally a full-body massage. In fact, until the mid-19th century, asking for a “shampoo” would get you pummeled by a masseur (or masseuse) and slathered with oils and lotions. Only lastly (if you lasted that long) would your hair be washed. By about 1860, however, “shampoo” had attained its exclusive modern meaning of “washing the hair.” Shortly thereafter, “shampoo” began to be used as a noun meaning either an act of shampooing or the special soap used on the hair.

[Rayne_Man]

Here is a similar answer from mindlesscrap.com

*Shampoo
The word comes from the Indian word champo. Early travelers to India noticed that sultans and nabobs had several servants who massaged their bodies after hot baths. Champo is the native term for “to press,” which was the method of massaging the body with knuckles. The term was taken back with the travelers to England, but only the wealthy could afford a professional bath attendant on the household staff. By 1860, shampooing was reduced to the operation of washing and rubbing only the scalp. *