'Antonia' originates from Latin, specifically the family name 'Antonius' with the feminine ending '-a'; 'Antonius' itself is likely of Etruscan origin and its original root meaning is uncertain.

'Antonia' was used in Classical Latin as the feminine form of the gens name 'Antonius', continued through Medieval Latin and into Romance languages (e.g. Italian, Spanish) as 'Antonia', and eventually entered modern English as the given name 'Antonia'.

Initially it identified someone 'of the Antonius family' (a family or clan name); over time it evolved into a standalone feminine personal name without a specific literal meaning.