noun additional proof that something that was believed (some fact or hypothesis or theory) is correct.
— synonyms: verification, check, substantiation
noun information that confirms or verifies.
noun making something valid by formally ratifying or confirming it.
— synonyms: ratification
noun a ceremony held in the synagogue (usually at Pentecost) to admit as adult members of the Jewish community young men and women who have successfully completed a course of study in Judaism.
noun a sacrament admitting a baptized person to full participation in the church.
Examples
“We will send you a written confirmation of your hotel booking.”
“The announcement in the newspaper was a confirmation of my suspicions.”