What is the meaning of confirmation?

noun

• Additional proof that something that was believed (some fact or hypothesis or theory) is correct.
  • usage: "fossils provided further confirmation of the evolutionary theory"
  • synonyms: verification, check, substantiation
• Information that confirms or verifies.
• Making something valid by formally ratifying or confirming it.
  • usage: "the ratification of the treaty"; "confirmation of the appointment"
  • synonyms: ratification
• 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.
• A sacrament admitting a baptized person to full participation in the church. .