1. It's a verb used to tell someone that s/he loses a right,possession,etc or has it taken away from her/him.
2. Something that's taken away from you or something that you've to pay because you've broken a rule or made a mistake.
1. Because she was fucking absent with what her boyfriend told her, she forfeited the right to appeal.
2. I've forfeited my freaking right to name my son after me father.
3. Yeah, if we lose this game we'll have to pay a forfeit.