a written agreement for insurance between an insurance company and a person who wants insurance

I took out a travel insurance policy before I boarded the plane. 我在上飞机之前买了旅行保险。

figurative There's one particular job I'm after but I'm applying for several others as an insurance policy (= because I might not get the job I want). 有一份工作我特别想得到，但为了保险起见我也申请了其他几份工作。