The Spanish word 'champú' comes from English 'shampoo', which has a fascinating journey from ancient Sanskrit. The word traces back to the Sanskrit 'capayati', meaning 'to knead or massage'. This evolved into the Hindi word 'cãpna', which meant 'to press or knead'. When the British colonized India, they borrowed this concept and the word became 'shampoo' in English, initially referring to the act of massaging but later specifically to hair cleaning products. Spanish then borrowed this word from English, adapting it to Spanish pronunciation and spelling as 'champú'.

There aren't many common Spanish words directly related to 'champú' since it's a relatively recent borrowing from English. The word stands somewhat alone in Spanish vocabulary, though you might encounter related forms like the verb 'champuar' (to shampoo), which is derived from 'champú'.

The English word 'shampoo' is obviously related to Spanish 'champú', as it's the direct source of the Spanish word. The spelling difference reflects Spanish adaptation of the English word to match Spanish pronunciation patterns, where 'sh' becomes 'ch' and the final stress is indicated with an accent mark. In English, 'shampoo' has also given rise to related forms like 'shampooing' and 'shampooed'.