| EQUIVALENTS |
| ANCIENT GREEK: Gaios |
| ANCIENT ROMAN: Caius, Gaius |
| BIBLICAL GREEK: Gaios |
| BIBLICAL LATIN: Gaius |
| BIBLICAL: Gaius |
| DANISH: Cai, Caj, Kai, Kaj, Kay |
| DUTCH: Kai |
| FINNISH: Kai |
| FRISIAN: Kai, Kay |
| GEORGIAN: Gaioz |
| GERMAN: Kai, Kay |
| LITHUANIAN: Kajus |
| NORWEGIAN: Cai, Caj, Kai, Kaj, Kay |
| PORTUGUESE (BRAZILIAN): Caio |
| SWEDISH: Cai, Caj, Kai, Kaj, Kay |
| FEMININE FORMS |
| POLISH: Gaja, Kaja |
| SLOVENE: Gaja, Kaja |
| OTHER FORMS |
| ARTHURIAN ROMANCE: Cai, Kay |
| WELSH MYTHOLOGY: Cai, Kay |