The Spanish word 'antigüedad' (meaning 'antiquity') comes from the Latin word 'antiquitas', which had the same meaning. 'Antiquitas' itself was formed from two parts: the Latin adjective 'antiquus' meaning 'ancient' or 'old', and the suffix '-tatis' which was used to form abstract nouns. Going even further back, 'antiquus' was derived from the Latin word 'ante' meaning 'before'.

In Spanish, this word maintained its structure but adapted to Spanish morphology: 'antiquus' became 'antiguo' and the Latin suffix '-tatis' evolved into the Spanish suffix '-edad', which is still used today to form abstract nouns from adjectives. The combination of these elements gave us 'antigüedad'.

A simpler and more commonly used Spanish word that's directly related to 'antigüedad' is 'antiguo', meaning 'ancient' or 'old'. This is actually the base word from which 'antigüedad' is formed. While 'antiguo' is an adjective that describes something as being old or ancient, 'antigüedad' is the abstract noun that refers to the quality or state of being ancient, or to an ancient object itself.

English speakers might recognize the connection between 'antigüedad' and the English words 'antique' and 'antiquity', which all come from the same Latin root 'antiquus'. The English word 'ante' (as in 'ante-room' or 'antebellum') is also related, coming from the Latin 'ante' meaning 'before'. This helps explain why 'antigüedad' and 'antique' both relate to things from an earlier time.