To pay, or promise to pay, an amount of money so that an accused person is not put in prison before the trial. If the accused person does not appear at the trial, the court can keep the money put up for bail.
Someone who takes responsibility for someone else's debts or promises, and guarantees that they will be paid or undertaken (done). It is also the name for the money put up as security that someone will appear in court. If they do not appear in court the money will be forfeited.