Vaticanus

Unknown. The connection to vāticinor (“to prophesy”) is folk-etymological.

• (Classical Latin) IPA^(key): [waː.tiːˈkaː.nʊs], [waː.tɪˈkaː.nʊs]
• (modern Italianate Ecclesiastical) IPA^(key): [va.t̪iˈkaː.nus]

Vātī̆cānus m (genitive Vātī̆cānī); second declension

1. The Vatican, a hill in Rome, Italy
2. Vatican City, the small state forming the headquarters of the Roman Catholic Church
3. The papacy, the government of the state and Catholic Church
4. (Roman mythology) alternative form of Vagitanus

Second-declension noun, singular only.