lifesaver
/ˈlaɪfˌseɪvə(r)/noun
1
- informal a thing that saves one from serious difficulty〈非正式〉省去麻烦（或困难）的东西（或物品）：
a microwave oven could be a lifesaver this Christmas.
今年圣诞微波炉会省去不少麻烦。
2
- （亦作 surf lifesaver）Austral./NZ a lifeguard working on a beach.〈澳/新西兰〉（海滨的）救生员。