The Spanish word 'etnia' meaning 'ethnic group' comes from Ancient Greek. It combines two Greek elements: 'ethnos' (ἔθνος) meaning 'people' or 'nation', and the suffix '-ia' which was used to form abstract nouns indicating a quality or state. These elements came together to create a word that refers to a group of people sharing common cultural, racial, linguistic, or national characteristics.

In Spanish, you might encounter related words like 'étnico' (ethnic) and 'etnicidad' (ethnicity), which share the same Greek root 'ethnos'. These words form a family of terms all relating to cultural and racial identity.

English speakers will recognize this word's connection to familiar terms like 'ethnic', 'ethnicity', and 'ethnology', all derived from the same Greek root 'ethnos'. The English word 'ethnic' is particularly close in both meaning and form to the Spanish 'etnia', making it easier to remember. While English typically uses 'ethnic group' where Spanish uses 'etnia', the concept is exactly the same.