a person who makes certain that something happens or that something is protected

The armed forces see themselves as the guarantors of free elections in the country. 武装部队把自己视作这个国家自由选举的保障。

someone who formally accepts responsibility for you or for something that belongs to you

You must have a guarantor in order to get a visa to enter the country. 要获得该国入境签证必须要有一个担保人。

a person or organization that promises to pay back a loan (= borrowed money) if the person or organization that borrowed it cannot pay it back

His father is a guarantor on the loan. 他父亲是贷款的担保人。