earnest money
 定金
 Ear·nest, n.
 1. Something given, or a part paid beforehand, as a pledge; pledge; handsel; a token of what is to come.
    Who hath also sealed us, and given the earnest of the Spirit in our hearts.   --2 Cor. i. 22.
 And from his coffers
 Received the golden earnest of our death.   --Shak.
 2. Law Something of value given by the buyer to the seller, by way of token or pledge, to bind the bargain and prove the sale.
 Earnest money Law, money paid as earnest, to bind a bargain or to ratify and prove a sale.
 Syn: -- Earnest, Pledge.
 Usage: These words are here compared as used in their figurative sense. Earnest is not so strong as pledge. An earnest, like first fruits, gives assurance, or at least a high probability, that more is coming of the same kind; a pledge, like money deposited, affords security and ground of reliance for the future. Washington gave earnest of his talent as commander by saving his troops after Braddock's defeat; his fortitude and that of his soldiers during the winter at Valley Forge might rightly be considered a pledge of their ultimate triumph.
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 earnest money
      n : money given by a buyer to a seller to bind a contract