smart money (n.)youdaoicibaDictYouDict[smart money 词源字典]
"money bet by those in the know," 1926, from smart (adj.). The same phrase earlier meant "money paid to sailors, soldiers, workers, etc., who have been disabled while on the job" (1690s), from a noun derivative of smart (v.). Also "money paid to obtain the discharge of a recruit" (1760), hence "money paid to escape some unpleasant situation" (1818). Sometimes in legal use, "damages in excess of injury done."[smart money etymology, smart money origin, 英语词源]