noun
Gregorian
Almost always used attributively in the compound グレゴリオ暦 (Gregorian calendar). Rarely used as a standalone noun.
日本は明治時代にグレゴリオ暦を採用した。
Japan adopted the Gregorian calendar in the Meiji period.
From Italian/Spanish Gregorio, ultimately from Latin Gregorius. Used in Japanese almost exclusively in the compound グレゴリオ暦 (Gregorian calendar).