noun
name day; baptism day
Refers to the feast day of the saint after whom a person is named, or the day of baptism. Common in Christian contexts.
彼の命名日は聖ヨハネの日です。
His name day is the feast of Saint John.
洗礼を受けた日を命名日として祝う。
They celebrate the day of baptism as their name day.