0 something, especially a way of getting help, that you depend on to lead your life in a satisfactory way: --
1 something, esp. a way of getting help, on which you depend: --
Airplanes are this Alaskan town’s lifeline.
2 something that will help a person, organization, or country to continue to exist or operate in the same way: --
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.
Vi kan slutföra det steg för steg hur lång vägen än är och den kan inte slutföras hur kort vägen än är om du inte ens markerar ditt fotavtryck.