The Spanish word 'tía' (meaning 'aunt') comes from the Latin word 'thia', which had the same meaning. The Latin term itself was borrowed from Ancient Greek 'theia' (θεία), which specifically referred to either a paternal or maternal aunt. The word underwent a simple phonetic evolution, with the 'th' sound becoming a 't' in Latin and Spanish, while maintaining its core meaning of referring to an aunt throughout its history.

The word 'tía' is already one of the most basic and common family terms in Spanish, and there aren't any simpler Spanish words that share its etymology. However, it's worth noting that 'tío' (uncle) follows a similar pattern, though it has a different etymological origin.

While English 'aunt' is not related to Spanish 'tía', there is an interesting connection in English words like 'theia-' or 'theo-' found in scientific terms. These come from the same Greek root that gave us 'tía', though they've taken on different meanings. For example, 'theiacide' is a rare term meaning the killing of an aunt, preserving that ancient Greek connection to aunts.