The Spanish word 'salitre' (meaning 'saltpeter') has a fascinating journey through multiple ancient languages. It begins with the Ancient Egyptian word 'ntr', which referred to natron (sodium carbonate), a natural mineral salt. This word was borrowed into Greek as 'nitron' (νίτρον), maintaining a similar meaning of natron or soda.

The Greek term was then adopted into Latin as 'nitrum'. In Latin, two words combined to form 'sal nitrum': 'sal' meaning 'salt' and 'nitrum' meaning 'natron/saltpeter'. This compound term specifically referred to saltpeter (potassium nitrate). The Latin compound then evolved through Catalan/Occitan as 'salnitre', finally reaching Spanish as 'salitre', preserving its meaning of saltpeter.

The Spanish word 'sal' (meaning 'salt') is directly related to 'salitre', as it comes from the same Latin root 'sal'. This connection makes sense since saltpeter is a type of salt compound. Another related Spanish word is 'salado' (salty), which shares the same root.

Several English words are etymologically related to 'salitre'. The word 'salt' comes from the same Latin root 'sal'. The element 'nitrogen' and the term 'niter' (another word for saltpeter) both trace back to the same Greek word 'nitron' that influenced 'salitre'. The scientific term 'nitrate' is also related, coming from the Latin 'nitrum'.