To establish the truth or correctness of something previously believed or suspected. The scientist conducted several experiments to confirm the hypothesis.
To acknowledge with definite assurance. The airline confirmed my flight reservation via email.
To make valid or binding by a formal or legal act. The board of directors confirmed the appointment of the new CEO.
To strengthen or make more firm. The recent events confirmed her belief in the importance of community support.
In certain Christian churches, to administer the rite of confirmation to (a baptised person). The bishop confirmed forty teenagers during the Easter vigil.