More than one option or set of resources: “Samantha has two strings to her bow; if her career in politics falls through, she can fall back on her law practice.”
More than one means of reaching an objective, as in Louise hasn't heard yet, but she's got two strings to her bow—she can always appeal to the chairman. This expression alludes to a well-prepared archer, who carries a spare string in case one fails. [Mid-1400s]
