a returnable amount of money is one that you get back if something that you use or borrow is still in good condition when you have finished using it 可返回的;可退回的
A returnable 150 euro deposit is payable on arrival. 到达后可返还150欧元的定金。
a returnable document is one that you must deal with and send back to someone, usually within a particular period of time and often to a court of law (尤指在一定期限内文件)必须交还的