To unintentionally reveal a secret, divulge undisclosed information, or expose someone.
To concede.
To formally hand over a bride to the bridegroom; often by her father.
To relinquish control over.
To concede an advantage in weight, time, height etc.
To make a gift of (something).
To inadvertently reveal any secret, particularly a secret that puts one at an advantage or disadvantage.
In card playing, to accidentally reveal one's cards or hand.