1A string, or each of a pair of strings, which may be drawn to close the mouth of a purse; a drawstring. In later use chiefly in similative expressions.
2figurative Chiefly in plural, especially in various phrases relating to the control of money, as "to hold the purse strings": to control expenditure.
Late Middle English; earliest use found in The Book of Margery Kempe. From purse + string.