life·line 
/ˈlaɪfˌlaɪn/ noun
plural life·lines /ˈlaɪfˌlaɪn/ noun [count] 1 : something which provides help or support that is needed for success or survival
▪ The river is the town's lifeline. ▪ The new jobs were an economic lifeline for a city in need of help. ▪ The radio was their lifeline to the outside world. 2 : a rope used for saving the life of someone (such as someone who has fallen into water)
▪ They threw a lifeline to the man overboard.
▪ The river is the town's lifeline. ▪ The new jobs were an economic lifeline for a city in need of help. ▪ The radio was their lifeline to the outside world.
▪ They threw a lifeline to the man overboard.
