The Spanish word 'otro' (meaning 'other') comes from the Latin word 'alter' (also meaning 'other'). The journey from Latin to Spanish involved several phonetic changes. First, the accusative form 'alterum' was commonly used, which then underwent a process called syncope (dropping of an unstressed vowel) to become 'altrum'. In Medieval Latin, this evolved to 'autrum', and finally reached the Spanish form 'otro' we use today. This transformation shows how Latin words were often simplified in their journey to becoming Spanish words, with sounds being dropped or modified to create easier pronunciation patterns.

The word 'otro' is one of the most basic and common Spanish words, so it's actually more likely that Spanish learners will encounter this word before meeting its derivatives. However, you might see it in compounds like 'nosotros' (meaning 'we/us'), which literally combines 'nos' ('us') with 'otros' ('others') to mean something like 'us others'.

English has several words that come from the same Latin root 'alter', including 'alternate', 'alternative', 'alter', and 'alteration'. While Spanish simplified the Latin word, English maintained closer to the original Latin form. You can see how all these words relate to the concept of 'otherness' or 'different options': an alternative is another choice, to alternate is to switch between different options, and to alter something is to make it into something other than what it was.