n.
  - a liquid preparation for washing the hair. 
▸a similar substance for cleaning a carpet, car, etc.
 - an act of washing with shampoo.
 
v.
 (shampoos, shampooing, shampooed)
 wash or clean with shampoo.
 
  Etymology
  C18 (in the sense ‘massage’): from Hindi cāṃpo! ‘press!’, imper. of cāṃpnā.