The proper spelling of the Latin phrase 'capitalis baro' is pronounced as /kəˈpɪ.təl ˈbær.oʊ/ as per the International Phonetic Alphabet (IPA). The first part of the phrase, 'capitalis,' is spelled with a 'c' instead of a 'k' due to the conventions of the Latin language. The second part, 'baro,' is spelled with an 'o' at the end instead of an 'e' as it is an ablative singular form. The phrase means 'chief baron' and was used to refer to the highest-ranking baron in medieval England.