An offer of recompense given by authority of law for the performance of some act for the public good; which, when the act has been performed, is to be paid; or it is the recompense actually paid. 2. A reward may be offered by the government or by a private person. In criminal prosecutions, a person may be a competent witness although he expects, on conviction of the prisoner, to receive a reward. 3. By the common law, informers, who are entitled under penal statutes to part of the penalty, are not in general competent witnesses. But when a statute can receive no execution, unless a party interested be a witness, then it seems proper to admit him, for the statute must not be rendered ineffectual for want of proof. Gilb. 114. In many acts of the legislature there is a provision that the informer shall be a witness, notwithstanding the reward. 1 Phil. Ev. 92, 99. A recompense or premium offered by government or an individual in return for special or extraordinary services to be performed, or for special attainments or achievements, or for some act resulting to the benefit of the public; as, a reward for useful inventions,; for the discovery and apprehension of criminals, for the restoration of lost property.